Fix markdown-header-face inherit from nil error

[markdown-mode.git] / markdown-mode.el

;;; markdown-mode.el --- Major mode for Markdown-formatted text -*- lexical-binding: t; -*-

;; Copyright (C) 2007-2017 Jason R. Blevins and markdown-mode
;; contributors (see the commit log for details).

;; Author: Jason R. Blevins <jrblevin@sdf.org>
;; Maintainer: Jason R. Blevins <jrblevin@sdf.org>
;; Created: May 24, 2007
;; Version: 2.1
;; Package-Requires: ((emacs "24") (cl-lib "0.5"))
;; Keywords: Markdown, GitHub Flavored Markdown, itex
;; URL: http://jblevins.org/projects/markdown-mode/

;; This file is not part of GNU Emacs.

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; markdown-mode is a major mode for editing [Markdown][]-formatted
;; text. The latest stable version is markdown-mode 2.1, released on
;; January 9, 2016. See the [release notes][] for details.
;; markdown-mode is free software, licensed under the GNU GPL.

;; ![Markdown Mode Screenshot](http://jblevins.org/projects/markdown-mode/screenshots/20160108-001.png)

;; [Markdown]: http://daringfireball.net/projects/markdown/
;; [release notes]: http://jblevins.org/projects/markdown-mode/rev-2-1

;;; Installation:

;; The recommended way to install markdown-mode is to install the package
;; from [MELPA Stable](https://stable.melpa.org/#/markdown-mode)
;; using `package.el'. First, configure `package.el' and the MELPA Stable
;; repository by adding the following to your `.emacs', `init.el',
;; or equivalent startup file:

;;     (require 'package)
;;     (add-to-list 'package-archives
;;                  '("melpa-stable" . "https://stable.melpa.org/packages/"))
;;     (package-initialize)

;; Then, after restarting Emacs or evaluating the above statements, issue
;; the following command: `M-x package-install RET markdown-mode RET`.
;; When installed this way, the major modes `markdown-mode' and `gfm-mode'
;; will be autoloaded and `markdown-mode' will be used for file names
;; ending in either `.md` or `.markdown`.
;;
;; Alternatively, if you manage loading packages with [use-package][]
;; then you can automatically install and configure `markdown-mode' by
;; adding a declaration such as this one to your init file (as an
;; example; adjust settings as desired):
;;
;;     (use-package markdown-mode
;;       :ensure t
;;       :commands (markdown-mode gfm-mode)
;;       :mode (("README\\.md\\'" . gfm-mode)
;;              ("\\.md\\'" . markdown-mode)
;;              ("\\.markdown\\'" . markdown-mode))
;;       :init (setq markdown-command "multimarkdown"))

;; [MELPA Stable]: http://stable.melpa.org/
;; [use-package]: https://github.com/jwiegley/use-package

;; **Direct Download**

;; Alternatively you can manually download and install markdown-mode.
;; First, download the [latest stable version][markdown-mode.el] and
;; save the file where Emacs can find it (i.e., a directory in your
;; `load-path'). You can then configure `markdown-mode' and `gfm-mode'
;; to load automatically by adding the following to your init file:

;;     (autoload 'markdown-mode "markdown-mode"
;;        "Major mode for editing Markdown files" t)
;;     (add-to-list 'auto-mode-alist '("\\.markdown\\'" . markdown-mode))
;;     (add-to-list 'auto-mode-alist '("\\.md\\'" . markdown-mode))
;;
;;     (autoload 'gfm-mode "markdown-mode"
;;        "Major mode for editing GitHub Flavored Markdown files" t)
;;     (add-to-list 'auto-mode-alist '("README\\.md\\'" . gfm-mode))

;; [markdown-mode.el]: http://jblevins.org/projects/markdown-mode/markdown-mode.el

;; **Development Version**

;; To follow or contribute to markdown-mode development, you can
;; browse or clone the Git repository
;; [on GitHub](https://github.com/jrblevin/markdown-mode):

;;     git clone https://github.com/jrblevin/markdown-mode.git

;; If you prefer to install and use the development version, which may
;; become unstable at some times, you can either clone the Git
;; repository as above or install markdown-mode from
;; [MELPA](https://melpa.org/#/markdown-mode).
;;
;; If you clone the repository directly, then make sure that Emacs can
;; find it by adding the following line to your startup file:
;;
;;     (add-to-list 'load-path "/path/to/markdown-mode/repository")

;; **Packaged Installation**

;; markdown-mode is also available in several package managers. You
;; may want to confirm that the package you install contains the
;; latest stable version first (and please notify the package
;; maintainer if not).
;;
;;    * Debian Linux: [elpa-markdown-mode][] and [emacs-goodies-el][]
;;    * Ubuntu Linux: [elpa-markdown-mode][elpa-ubuntu] and [emacs-goodies-el][emacs-goodies-el-ubuntu]
;;    * RedHat and Fedora Linux: [emacs-goodies][]
;;    * NetBSD: [textproc/markdown-mode][]
;;    * MacPorts: [markdown-mode.el][macports-package] ([pending][macports-ticket])
;;    * FreeBSD: [textproc/markdown-mode.el][freebsd-port]
;;
;;  [elpa-markdown-mode]: https://packages.debian.org/sid/lisp/elpa-markdown-mode
;;  [elpa-ubuntu]: http://packages.ubuntu.com/search?keywords=elpa-markdown-mode
;;  [emacs-goodies-el]: http://packages.debian.org/emacs-goodies-el
;;  [emacs-goodies-el-ubuntu]: http://packages.ubuntu.com/search?keywords=emacs-goodies-el
;;  [emacs-goodies]: https://apps.fedoraproject.org/packages/emacs-goodies
;;  [textproc/markdown-mode]: http://pkgsrc.se/textproc/markdown-mode
;;  [macports-package]: https://trac.macports.org/browser/trunk/dports/editors/markdown-mode.el/Portfile
;;  [macports-ticket]: http://trac.macports.org/ticket/35716
;;  [freebsd-port]: http://svnweb.freebsd.org/ports/head/textproc/markdown-mode.el

;; **Dependencies**

;; `markdown-mode' depends on `cl-lib', which has been bundled with
;; GNU Emacs since 24.3.  Users of GNU Emacs 24.1 and 24.2 can install
;; `cl-lib' with `package.el'.

;;; Usage:

;; Keybindings are grouped by prefixes based on their function.  For
;; example, the commands for inserting links are grouped under `C-c
;; C-a`, where the `C-a` is a mnemonic for the HTML `<a>` tag.  In
;; other cases, the connection to HTML is not direct.  For example,
;; commands dealing with headings begin with `C-c C-t` (mnemonic:
;; titling).  The primary commands in each group will are described
;; below.  You can obtain a list of all keybindings by pressing `C-c
;; C-h`.  Movement and shifting commands tend to be associated with
;; paired delimiters such as `M-{` and `M-}` or `C-c <` and `C-c >`.
;; Outline navigation keybindings the same as in `org-mode'.  Finally,
;; commands for running Markdown or doing maintenance on an open file
;; are grouped under the `C-c C-c` prefix.  The most commonly used
;; commands are described below.  You can obtain a list of all
;; keybindings by pressing `C-c C-h`.
;;
;;   * Hyperlinks: `C-c C-a`
;;
;;     In this group, `C-c C-a l` inserts an inline link of the form
;;     `[text](url)`.  The link text is determined as follows.  First,
;;     if there is an active region (i.e., when transient mark mode is
;;     on and the mark is active), use it as the link text.  Second,
;;     if the point is at a word, use that word as the link text.  In
;;     these two cases, the original text will be replaced with the
;;     link and point will be left at the position for inserting a
;;     URL.  Otherwise, insert empty link markup and place the point
;;     for inserting the link text.
;;
;;     `C-c C-a L` inserts a reference link of the form `[text][label]`
;;     and, optionally, a corresponding reference label definition.
;;     The link text is determined in the same way as with an inline
;;     link (using the region, when active, or the word at the point),
;;     but instead of inserting empty markup as a last resort, the
;;     link text will be read from the minibuffer.  The reference
;;     label will be read from the minibuffer in both cases, with
;;     completion from the set of currently defined references.  To
;;     create an implicit reference link, press `RET` to accept the
;;     default, an empty label.  If the entered referenced label is
;;     not defined, additionally prompt for the URL and (optional)
;;     title.  If a URL is provided, a reference definition will be
;;     inserted in accordance with `markdown-reference-location'.
;;     If a title is given, it will be added to the end of the
;;     reference definition and will be used to populate the title
;;     attribute when converted to XHTML.
;;
;;     `C-c C-a u` inserts a bare url, delimited by angle brackets.  When
;;     there is an active region, the text in the region is used as the
;;     URL.  If the point is at a URL, that url is used.  Otherwise,
;;     insert angle brackets and position the point in between them
;;     for inserting the URL.
;;
;;     `C-c C-a f` inserts a footnote marker at the point, inserts a
;;     footnote definition below, and positions the point for
;;     inserting the footnote text.  Note that footnotes are an
;;     extension to Markdown and are not supported by all processors.
;;
;;     `C-c C-a w` behaves much like the inline link insertion command
;;     and inserts a wiki link of the form `[[WikiLink]]`.  If there
;;     is an active region, use the region as the link text.  If the
;;     point is at a word, use the word as the link text.  If there is
;;     no active region and the point is not at word, simply insert
;;     link markup.  Note that wiki links are an extension to Markdown
;;     and are not supported by all processors.
;;
;;   * Images: `C-c C-i`
;;
;;     `C-c C-i i` inserts markup for an inline image, using the
;;     active region or the word at point, if any, as the alt text.
;;     `C-c C-i I` behaves similarly and inserts a reference-style
;;     image.
;;
;;     Local images associated with image links may be displayed
;;     inline in the buffer by pressing `C-c C-i C-t`
;;     (`markdown-toggle-inline-images'). This is a toggle command, so
;;     pressing this once again will remove inline images.
;;
;;   * Styles: `C-c C-s`
;;
;;     `C-c C-s e` inserts markup to make a region or word italic (`e`
;;     for `<em>` or emphasis).  If there is an active region, make
;;     the region italic.  If the point is at a non-italic word, make
;;     the word italic.  If the point is at an italic word or phrase,
;;     remove the italic markup.  Otherwise, simply insert italic
;;     delimiters and place the cursor in between them.  Similarly,
;;     use `C-c C-s s` for bold (`<strong>`), `C-c C-s c` for
;;     inline code (`<code>`), and `C-c C-s k` for inserting `<kbd>`
;;     tags.
;;
;;     `C-c C-s b` inserts a blockquote using the active region, if any,
;;     or starts a new blockquote.  `C-c C-s C-b` is a variation which
;;     always operates on the region, regardless of whether it is
;;     active or not.  The appropriate amount of indentation, if any,
;;     is calculated automatically given the surrounding context, but
;;     may be adjusted later using the region indentation commands.
;;
;;     `C-c C-s p` behaves similarly for inserting preformatted code
;;     blocks, with `C-c C-s C-p` being the region-only counterpart.
;;
;;   * Headings: `C-c C-t`
;;
;;     All heading insertion commands use the text in the active
;;     region, if any, as the heading text.  Otherwise, if the current
;;     line is not blank, they use the text on the current line.
;;     Finally, the setext commands will prompt for heading text if
;;     there is no active region and the current line is blank.
;;
;;     `C-c C-t h` inserts a heading with automatically chosen type and
;;     level (both determined by the previous heading).  `C-c C-t H`
;;     behaves similarly, but uses setext (underlined) headings when
;;     possible, still calculating the level automatically.
;;     In cases where the automatically-determined level is not what
;;     you intended, the level can be quickly promoted or demoted
;;     (as described below).  Alternatively, a `C-u` prefix can be
;;     given to insert a heading promoted by one level or a `C-u C-u`
;;     prefix can be given to insert a heading demoted by one level.
;;
;;     To insert a heading of a specific level and type, use `C-c C-t 1`
;;     through `C-c C-t 6` for atx (hash mark) headings and `C-c C-t !` or
;;     `C-c C-t @` for setext headings of level one or two, respectively.
;;     Note that `!` is `S-1` and `@` is `S-2`.
;;
;;     If the point is at a heading, these commands will replace the
;;     existing markup in order to update the level and/or type of the
;;     heading.  To remove the markup of the heading at the point,
;;     press `C-c C-k` to kill the heading and press `C-y` to yank the
;;     heading text back into the buffer.
;;
;;   * Horizontal Rules: `C-c -`
;;
;;     `C-c -` inserts a horizontal rule.  By default, insert the
;;     first string in the list `markdown-hr-strings' (the most
;;     prominent rule).  With a `C-u` prefix, insert the last string.
;;     With a numeric prefix `N`, insert the string in position `N`
;;     (counting from 1).
;;
;;   * Markdown and Maintenance Commands: `C-c C-c`
;;
;;     *Compile:* `C-c C-c m` will run Markdown on the current buffer
;;     and show the output in another buffer.  *Preview*: `C-c C-c p`
;;     runs Markdown on the current buffer and previews, stores the
;;     output in a temporary file, and displays the file in a browser.
;;     *Export:* `C-c C-c e` will run Markdown on the current buffer
;;     and save the result in the file `basename.html`, where
;;     `basename` is the name of the Markdown file with the extension
;;     removed.  *Export and View:* press `C-c C-c v` to export the
;;     file and view it in a browser.  *Open:* `C-c C-c o` will open
;;     the Markdown source file directly using `markdown-open-command'.
;;     *Live Export*: Press `C-c C-c l` to turn on
;;     `markdown-live-preview-mode' to view the exported output
;;     side-by-side with the source Markdown. **For all export commands,
;;     the output file will be overwritten without notice.**
;;     `markdown-live-preview-window-function' can be customized to open
;;     in a browser other than `eww'.  If you want to force the
;;     preview window to appear at the bottom or right, you can
;;     customize `markdown-split-window-direction`.
;;
;;     To summarize:
;;
;;       - `C-c C-c m`: `markdown-command' > `*markdown-output*` buffer.
;;       - `C-c C-c p`: `markdown-command' > temporary file > browser.
;;       - `C-c C-c e`: `markdown-command' > `basename.html`.
;;       - `C-c C-c v`: `markdown-command' > `basename.html` > browser.
;;       - `C-c C-c w`: `markdown-command' > kill ring.
;;       - `C-c C-c o`: `markdown-open-command'.
;;       - `C-c C-c l`: `markdown-live-preview-mode' > `*eww*` buffer.
;;
;;     `C-c C-c c` will check for undefined references.  If there are
;;     any, a small buffer will open with a list of undefined
;;     references and the line numbers on which they appear.  In Emacs
;;     22 and greater, selecting a reference from this list and
;;     pressing `RET` will insert an empty reference definition at the
;;     end of the buffer.  Similarly, selecting the line number will
;;     jump to the corresponding line.
;;
;;     `C-c C-c n` renumbers any ordered lists in the buffer that are
;;     out of sequence.
;;
;;     `C-c C-c ]` completes all headings and normalizes all horizontal
;;     rules in the buffer.
;;
;;   * Following Links: `C-c C-o`
;;
;;     Press `C-c C-o` when the point is on an inline or reference
;;     link to open the URL in a browser.  When the point is at a
;;     wiki link, open it in another buffer (in the current window,
;;     or in the other window with the `C-u` prefix).  Use `M-p` and
;;     `M-n` to quickly jump to the previous or next link of any type.
;;
;;   * Jumping: `C-c C-l`
;;
;;     Use `C-c C-l` to jump from the object at point to its counterpart
;;     elsewhere in the text, when possible.  Jumps between reference
;;     links and definitions; between footnote markers and footnote
;;     text.  If more than one link uses the same reference name, a
;;     new buffer will be created containing clickable buttons for jumping
;;     to each link.  You may press `TAB` or `S-TAB` to jump between
;;     buttons in this window.
;;
;;   * Promotion and Demotion: `C-c C--` and `C-c C-=`
;;
;;     Headings, horizontal rules, and list items can be promoted and
;;     demoted, as well as bold and italic text.  For headings,
;;     "promotion" means *decreasing* the level (i.e., moving from
;;     `<h2>` to `<h1>`) while "demotion" means *increasing* the
;;     level.  For horizontal rules, promotion and demotion means
;;     moving backward or forward through the list of rule strings in
;;     `markdown-hr-strings'.  For bold and italic text, promotion and
;;     demotion means changing the markup from underscores to asterisks.
;;     Press `C-c C--` or `M-LEFT` to promote the element at the point
;;     if possible.
;;
;;     To remember these commands, note that `-` is for decreasing the
;;     level (promoting), and `=` (on the same key as `+`) is for
;;     increasing the level (demoting).  Similarly, the left and right
;;     arrow keys indicate the direction that the atx heading markup
;;     is moving in when promoting or demoting.
;;
;;   * Completion: `C-c C-]`
;;
;;     Complete markup is in normalized form, which means, for
;;     example, that the underline portion of a setext header is the
;;     same length as the heading text, or that the number of leading
;;     and trailing hash marks of an atx header are equal and that
;;     there is no extra whitespace in the header text.  `C-c C-]`
;;     completes the markup at the point, if it is determined to be
;;     incomplete.
;;
;;   * Editing Lists: `M-RET`, `M-UP`, `M-DOWN`, `M-LEFT`, and `M-RIGHT`
;;
;;     New list items can be inserted with `M-RET` or `C-c C-j`.  This
;;     command determines the appropriate marker (one of the possible
;;     unordered list markers or the next number in sequence for an
;;     ordered list) and indentation level by examining nearby list
;;     items.  If there is no list before or after the point, start a
;;     new list.  Prefix this command by `C-u` to decrease the
;;     indentation by one level.  Prefix this command by `C-u C-u` to
;;     increase the indentation by one level.
;;
;;     Existing list items can be moved up or down with `M-UP` or
;;     `M-DOWN` and indented or exdented with `M-RIGHT` or `M-LEFT`.
;;
;;   * Editing Subtrees: `M-S-UP`, `M-S-DOWN`, `M-S-LEFT`, and `M-S-RIGHT`
;;
;;     Entire subtrees of ATX headings can be promoted and demoted
;;     with `M-S-LEFT` and `M-S-RIGHT`, which mirror the bindings
;;     for promotion and demotion of list items. Similarly, subtrees
;;     can be moved up and down with `M-S-UP` and `M-S-DOWN`.
;;
;;     Please note the following "boundary" behavior for promotion and
;;     demotion.  Any level-six headings will not be demoted further
;;     (i.e., they remain at level six, since Markdown and HTML define
;;     only six levels) and any level-one headings will promoted away
;;     entirely (i.e., heading markup will be removed, since a
;;     level-zero heading is not defined).
;;
;;   * Shifting the Region: `C-c <` and `C-c >`
;;
;;     Text in the region can be indented or exdented as a group using
;;     `C-c >` to indent to the next indentation point (calculated in
;;     the current context), and `C-c <` to exdent to the previous
;;     indentation point.  These keybindings are the same as those for
;;     similar commands in `python-mode'.
;;
;;   * Killing Elements: `C-c C-k`
;;
;;     Press `C-c C-k` to kill the thing at point and add important
;;     text, without markup, to the kill ring.  Possible things to
;;     kill include (roughly in order of precedece): inline code,
;;     headings, horizonal rules, links (add link text to kill ring),
;;     images (add alt text to kill ring), angle URIs, email
;;     addresses, bold, italics, reference definitions (add URI to
;;     kill ring), footnote markers and text (kill both marker and
;;     text, add text to kill ring), and list items.
;;
;;   * Outline Navigation: `C-c C-n`, `C-c C-p`, `C-c C-f`, `C-c C-b`, and `C-c C-u`
;;
;;     Navigation between headings is possible using `outline-mode'.
;;     Use `C-c C-n` and `C-c C-p` to move between the next and previous
;;     visible headings.  Similarly, `C-c C-f` and `C-c C-b` move to the
;;     next and previous visible headings at the same level as the one
;;     at the point.  Finally, `C-c C-u` will move up to a lower-level
;;     (higher precedence) visible heading.
;;
;;   * Movement by Paragraph or Block: `M-{` and `M-}`
;;
;;     The definition of a "paragraph" is slightly different in
;;     markdown-mode than, say, text-mode, because markdown-mode
;;     supports filling for list items and respects hard line breaks,
;;     both of which break paragraphs.  So, markdown-mode overrides
;;     the usual paragraph navigation commands `M-{` and `M-}` so that
;;     with a `C-u` prefix, these commands jump to the beginning or
;;     end of an entire block of text, respectively, where "blocks"
;;     are separated by one or more lines.
;;
;;   * Movement by Defun: `C-M-a`, `C-M-e`, and `C-M-h`
;;
;;     The usual Emacs commands can be used to move by defuns
;;     (top-level major definitions).  In markdown-mode, a defun is a
;;     section.  As usual, `C-M-a` will move the point to the
;;     beginning of the current or preceding defun, `C-M-e` will move
;;     to the end of the current or following defun, and `C-M-h` will
;;     put the region around the entire defun.
;;
;; As noted, many of the commands above behave differently depending
;; on whether Transient Mark mode is enabled or not.  When it makes
;; sense, if Transient Mark mode is on and the region is active, the
;; command applies to the text in the region (e.g., `C-c C-s s` makes the
;; region bold).  For users who prefer to work outside of Transient
;; Mark mode, since Emacs 22 it can be enabled temporarily by pressing
;; `C-SPC C-SPC`.  When this is not the case, many commands then
;; proceed to look work with the word or line at the point.
;;
;; When applicable, commands that specifically act on the region even
;; outside of Transient Mark mode have the same keybinding as their
;; standard counterpart, but the letter is uppercase.  For example,
;; `markdown-insert-blockquote' is bound to `C-c C-s b` and only acts on
;; the region in Transient Mark mode while `markdown-blockquote-region'
;; is bound to `C-c C-s B` and always applies to the region (when nonempty).
;;
;; Note that these region-specific functions are useful in many
;; cases where it may not be obvious.  For example, yanking text from
;; the kill ring sets the mark at the beginning of the yanked text
;; and moves the point to the end.  Therefore, the (inactive) region
;; contains the yanked text.  So, `C-y` followed by `C-c C-s C-b` will
;; yank text and turn it into a blockquote.
;;
;; markdown-mode attempts to be flexible in how it handles
;; indentation.  When you press `TAB` repeatedly, the point will cycle
;; through several possible indentation levels corresponding to things
;; you might have in mind when you press `RET` at the end of a line or
;; `TAB`.  For example, you may want to start a new list item,
;; continue a list item with hanging indentation, indent for a nested
;; pre block, and so on.  Exdention is handled similarly when backspace
;; is pressed at the beginning of the non-whitespace portion of a line.
;;
;; markdown-mode supports outline-minor-mode as well as org-mode-style
;; visibility cycling for atx- or hash-style headings.  There are two
;; types of visibility cycling: Pressing `S-TAB` cycles globally between
;; the table of contents view (headings only), outline view (top-level
;; headings only), and the full document view.  Pressing `TAB` while the
;; point is at a heading will cycle through levels of visibility for the
;; subtree: completely folded, visible children, and fully visible.
;; Note that mixing hash and underline style headings will give undesired
;; results.

;;; Customization:

;; Although no configuration is *necessary* there are a few things
;; that can be customized.  The `M-x customize-mode` command
;; provides an interface to all of the possible customizations:
;;
;;   * `markdown-command' - the command used to run Markdown (default:
;;     `markdown`).  This variable may be customized to pass
;;     command-line options to your Markdown processor of choice.
;;
;;   * `markdown-command-needs-filename' - set to `t' if
;;     `markdown-command' does not accept standard input (default:
;;     `nil').  When `nil', `markdown-mode' will pass the Markdown
;;     content to `markdown-command' using standard input (`stdin`).
;;     When set to `t', `markdown-mode' will pass the name of the file
;;     as the final command-line argument to `markdown-command'.  Note
;;     that in the latter case, you will only be able to run
;;     `markdown-command' from buffers which are visiting a file.
;;
;;   * `markdown-open-command' - the command used for calling a standalone
;;     Markdown previewer which is capable of opening Markdown source files
;;     directly (default: `nil').  This command will be called
;;     with a single argument, the filename of the current buffer.
;;     A representative program is the Mac app [Marked 2][], a
;;     live-updating Markdown previewer which can be [called from a
;;     simple shell script](http://jblevins.org/log/marked-2-command).
;;
;;   * `markdown-hr-strings' - list of strings to use when inserting
;;     horizontal rules.  Different strings will not be distinguished
;;     when converted to HTML--they will all be converted to
;;     `<hr/>`--but they may add visual distinction and style to plain
;;     text documents.  To maintain some notion of promotion and
;;     demotion, keep these sorted from largest to smallest.
;;
;;   * `markdown-bold-underscore' - set to a non-nil value to use two
;;     underscores when inserting bold text instead of two asterisks
;;     (default: `nil').
;;
;;   * `markdown-italic-underscore' - set to a non-nil value to use
;;     underscores when inserting italic text instead of asterisks
;;     (default: `nil').
;;
;;   * `markdown-asymmetric-header' - set to a non-nil value to use
;;     asymmetric header styling, placing header characters only on
;;     the left of headers (default: `nil').
;;
;;   * `markdown-header-scaling' - set to a non-nil value to use
;;     a variable-pitch font for headings where the size corresponds
;;     to the level of the heading (default: `nil').
;;
;;   * `markdown-header-scaling-values' - list of scaling values,
;;     relative to baseline, for headers of levels one through six,
;;     used when `markdown-header-scaling' is non-nil
;;     (default: `(list 1.8 1.4 1.2 1.0 1.0 1.0)`).
;;
;;   * `markdown-list-indent-width' - depth of indentation for lists
;;     when inserting, promoting, and demoting list items (default: 4).
;;
;;   * `markdown-indent-function' - the function to use for automatic
;;     indentation (default: `markdown-indent-line').
;;
;;   * `markdown-indent-on-enter' - set to a non-nil value to
;;     automatically indent new lines and/or continue lists when the
;;     enter key is pressed (default: `t')
;;
;;   * `markdown-enable-wiki-links' - syntax highlighting for wiki
;;     links (default: `nil').  Set this to a non-nil value to turn on
;;     wiki link support by default.  Wiki link support can be toggled
;;     later using the function `markdown-toggle-wiki-links'."
;;
;;   * `markdown-wiki-link-alias-first' - set to a non-nil value to
;;     treat aliased wiki links like `[[link text|PageName]]`
;;     (default: `t').  When set to nil, they will be treated as
;;     `[[PageName|link text]]'.
;;
;;   * `markdown-uri-types' - a list of protocol schemes (e.g., "http")
;;     for URIs that `markdown-mode' should highlight.
;;
;;   * `markdown-enable-math' - syntax highlighting for LaTeX
;;     fragments (default: `nil').  Set this to `t' to turn on math
;;     support by default.  Math support can be enabled, disabled, or
;;     toggled later using the function `markdown-toggle-math'."
;;
;;   * `markdown-css-paths' - CSS files to link to in XHTML output
;;     (default: `nil`).
;;
;;   * `markdown-content-type' - when set to a nonempty string, an
;;     `http-equiv` attribute will be included in the XHTML `<head>`
;;     block (default: `""`).  If needed, the suggested values are
;;     `application/xhtml+xml` or `text/html`.  See also:
;;     `markdown-coding-system'.
;;
;;   * `markdown-coding-system' - used for specifying the character
;;     set identifier in the `http-equiv` attribute when included
;;     (default: `nil').  See `markdown-content-type', which must
;;     be set before this variable has any effect.  When set to `nil',
;;     `buffer-file-coding-system' will be used to automatically
;;     determine the coding system string (falling back to
;;     `iso-8859-1' when unavailable).  Common settings are `utf-8'
;;     and `iso-latin-1'.
;;
;;   * `markdown-xhtml-header-content' - additional content to include
;;     in the XHTML `<head>` block (default: `""`).
;;
;;   * `markdown-xhtml-standalone-regexp' - a regular expression which
;;     `markdown-mode' uses to determine whether the output of
;;     `markdown-command' is a standalone XHTML document or an XHTML
;;     fragment (default: `"^\\(<\\?xml\\|<!DOCTYPE\\|<html\\)"`).  If
;;     this regular expression not matched in the first five lines of
;;     output, `markdown-mode' assumes the output is a fragment and
;;     adds a header and footer.
;;
;;   * `markdown-link-space-sub-char' - a character to replace spaces
;;     when mapping wiki links to filenames (default: `"_"`).
;;     For example, use an underscore for compatibility with the
;;     Python Markdown WikiLinks extension.  In `gfm-mode', this is
;;     set to `"-"` to conform with GitHub wiki links.
;;
;;   * `markdown-reference-location' - where to insert reference
;;     definitions (default: `header`).  The possible locations are
;;     the end of the document (`end`), after the current block
;;     (`immediately`), before the next header (`header`).
;;
;;   * `markdown-footnote-location' - where to insert footnote text
;;     (default: `end`).  The set of location options is the same as
;;     for `markdown-reference-location'.
;;
;;   * `markdown-nested-imenu-heading-index' - Use nested imenu
;;     heading instead of a flat index (default: `nil').  A nested
;;     index may provide more natural browsing from the menu, but a
;;     flat list may allow for faster keyboard navigation via tab
;;     completion.
;;
;;   * `comment-auto-fill-only-comments' - variable is made
;;     buffer-local and set to `nil' by default.  In programming
;;     language modes, when this variable is non-nil, only comments
;;     will be filled by auto-fill-mode.  However, comments in
;;     Markdown documents are rare and the most users probably intend
;;     for the actual content of the document to be filled.  Making
;;     this variable buffer-local allows `markdown-mode' to override
;;     the default behavior induced when the global variable is non-nil.
;;
;;   * `markdown-gfm-additional-languages', - additional languages to
;;     make available, aside from those predefined in
;;     `markdown-gfm-recognized-languages', when inserting GFM code
;;     blocks (default: `nil`). Language strings must have be trimmed
;;     of whitespace and not contain any curly braces. They may be of
;;     arbitrary capitalization, though.
;;
;;   * `markdown-gfm-use-electric-backquote' - use
;;     `markdown-electric-backquote' for interactive insertion of GFM
;;     code blocks when backquote is pressed three times (default: `t`).
;;
;;   * `markdown-make-gfm-checkboxes-buttons' - Whether GitHub
;;     Flavored Markdown style task lists (checkboxes) should be
;;     turned into buttons that can be toggled with mouse-1 or RET. If
;;     non-nil (default), then buttons are enabled.  This works in
;;     `markdown-mode' as well as `gfm-mode'.
;;
;; Additionally, the faces used for syntax highlighting can be modified to
;; your liking by issuing `M-x customize-group RET markdown-faces`
;; or by using the "Markdown Faces" link at the bottom of the mode
;; customization screen.
;;
;; [Marked 2]: https://itunes.apple.com/us/app/marked-2/id890031187?mt=12&uo=4&at=11l5Vs&ct=mm

;;; Extensions:

;; Besides supporting the basic Markdown syntax, Markdown Mode also
;; includes syntax highlighting for `[[Wiki Links]]`.  This can be
;; enabled by setting `markdown-enable-wiki-links' to a non-nil value.
;; Wiki links may be followed by pressing `C-c C-o` when the point
;; is at a wiki link.  Use `M-p` and `M-n` to quickly jump to the
;; previous and next links (including links of other types).
;; Aliased or piped wiki links of the form `[[link text|PageName]]`
;; are also supported.  Since some wikis reverse these components, set
;; `markdown-wiki-link-alias-first' to nil to treat them as
;; `[[PageName|link text]]`.  If `markdown-wiki-link-fontify-missing'
;; is also non-nil, Markdown Mode will highlight wiki links with
;; missing target file in a different color.  By default, Markdown
;; Mode only searches for target files in the current directory.
;; Search in subdirectories can be enabled by setting
;; `markdown-wiki-link-search-subdirectories' to a non-nil value.
;; Sequential parent directory search (as in [Ikiwiki][]) can be
;; enabled by setting `markdown-wiki-link-search-parent-directories'
;; to a non-nil value.
;;
;; [Ikiwiki]: https://ikiwiki.info
;;
;; [SmartyPants][] support is possible by customizing `markdown-command'.
;; If you install `SmartyPants.pl` at, say, `/usr/local/bin/smartypants`,
;; then you can set `markdown-command' to `"markdown | smartypants"`.
;; You can do this either by using `M-x customize-group markdown`
;; or by placing the following in your `.emacs` file:
;;
;;     (setq markdown-command "markdown | smartypants")
;;
;; [SmartyPants]: http://daringfireball.net/projects/smartypants/
;;
;; Syntax highlighting for mathematical expressions written
;; in LaTeX (only expressions denoted by `$..$`, `$$..$$`, or `\[..\]`)
;; can be enabled by setting `markdown-enable-math' to a non-nil value,
;; either via customize or by placing `(setq markdown-enable-math t)`
;; in `.emacs`, and then restarting Emacs or calling
;; `markdown-reload-extensions'.

;;; GitHub Flavored Markdown (GFM):

;; A [GitHub Flavored Markdown][GFM] mode, `gfm-mode', is also
;; available.  The GitHub implementation differs slightly from
;; standard Markdown in that it supports things like different
;; behavior for underscores inside of words, automatic linking of
;; URLs, strikethrough text, and fenced code blocks with an optional
;; language keyword.
;;
;; The GFM-specific features above apply to `README.md` files, wiki
;; pages, and other Markdown-formatted files in repositories on
;; GitHub.  GitHub also enables [additional features][GFM comments] for
;; writing on the site (for issues, pull requests, messages, etc.)
;; that are further extensions of GFM.  These features include task
;; lists (checkboxes), newlines corresponding to hard line breaks,
;; auto-linked references to issues and commits, wiki links, and so
;; on.  To make matters more confusing, although task lists are not
;; part of [GFM proper][GFM], [since 2014][] they are rendered (in a
;; read-only fashion) in all Markdown documents in repositories on the
;; site.  These additional extensions are supported to varying degrees
;; by `markdown-mode' and `gfm-mode' as described below.
;;
;; * **URL autolinking:** Both `markdown-mode' and `gfm-mode' support
;;   highlighting of URLs without angle brackets.
;;
;; * **Multiple underscores in words:** You must enable `gfm-mode' to
;;   toggle support for underscores inside of words. In this mode
;;   variable names such as `a_test_variable` will not trigger
;;   emphasis (italics).
;;
;; * **Fenced code blocks:** Code blocks quoted with backticks, with
;;   optional programming language keywords, are highlighted in
;;   both `markdown-mode' and `gfm-mode'.  They can be inserted with
;;   `C-c C-s P`.  If there is an active region, the text in the
;;   region will be placed inside the code block.  You will be
;;   prompted for the name of the language, but may press enter to
;;   continue without naming a language.
;;
;; * **Strikethrough:** Strikethrough text is only supported in
;;   `gfm-mode' and can be inserted (and toggled) using `C-c C-s d`.
;;   Following the mnemonics for the other style keybindings, the
;;   letter `d` coincides with the HTML tag `<del>`.
;;
;; * **Task lists:** GFM task lists will be rendered as checkboxes
;;   (Emacs buttons) in both `markdown-mode' and `gfm-mode' when
;;   `markdown-make-gfm-checkboxes-buttons' is set to a non-nil value
;;   (and it is set to t by default).  These checkboxes can be
;;   toggled by clicking `mouse-1`, pressing `RET` over the button,
;;   or by pressing `C-c C-x C-x` with the point anywhere in the task
;;   list item.
;;
;; * **Wiki links:** Generic wiki links are supported in
;;   `markdown-mode', but in `gfm-mode' specifically they will be
;;   treated as they are on GitHub: spaces will be replaced by hyphens
;;   in filenames and the first letter of the filename will be
;;   capitalized.  For example, `[[wiki link]]' will map to a file
;;   named `Wiki-link` with the same extension as the current file.
;;   If a file with this name does not exist in the current directory,
;;   the first match in a subdirectory, if any, will be used instead.
;;
;; * **Newlines:** Neither `markdown-mode' nor `gfm-mode' do anything
;;   specifically with respect to newline behavior.  If you use
;;   `gfm-mode' mostly to write text for comments or issues on the
;;   GitHub site--where newlines are significant and correspond to
;;   hard line breaks--then you may want to enable `visual-line-mode'
;;   for line wrapping in buffers.  You can do this with a
;;   `gfm-mode-hook' as follows:
;;
;;         ;; Use visual-line-mode in gfm-mode
;;         (defun my-gfm-mode-hook ()
;;           (visual-line-mode 1))
;;         (add-hook 'gfm-mode-hook 'my-gfm-mode-hook)
;;
;; * **Preview:** GFM-specific preview can be powered by setting
;;   `markdown-command' to use [Docter][].  This may also be
;;   configured to work with [Marked 2][] for `markdown-open-command'.
;;
;; [GFM]: http://github.github.com/github-flavored-markdown/
;; [GFM comments]: https://help.github.com/articles/writing-on-github/
;; [since 2014]: https://github.com/blog/1825-task-lists-in-all-markdown-documents
;; [Docter]: https://github.com/alampros/Docter

;;; Acknowledgments:

;; markdown-mode has benefited greatly from the efforts of the many
;; volunteers who have sent patches, test cases, bug reports,
;; suggestions, helped with packaging, etc.  Thank you for your
;; contributions!  See the [contributors graph][contrib] for details.
;;
;;  [contrib]: https://github.com/jrblevin/markdown-mode/graphs/contributors

;;; Bugs:

;; markdown-mode is developed and tested primarily for compatibility
;; with GNU Emacs 24.3 and later.  If you find any bugs in
;; markdown-mode, please construct a test case or a patch and open a
;; ticket on the [GitHub issue tracker][issues].
;;
;;  [issues]: https://github.com/jrblevin/markdown-mode/issues

;;; History:

;; markdown-mode was written and is maintained by Jason Blevins.  The
;; first version was released on May 24, 2007.
;;
;;   * 2007-05-24: [Version 1.1][]
;;   * 2007-05-25: [Version 1.2][]
;;   * 2007-06-05: [Version 1.3][]
;;   * 2007-06-29: [Version 1.4][]
;;   * 2007-10-11: [Version 1.5][]
;;   * 2008-06-04: [Version 1.6][]
;;   * 2009-10-01: [Version 1.7][]
;;   * 2011-08-12: [Version 1.8][]
;;   * 2011-08-15: [Version 1.8.1][]
;;   * 2013-01-25: [Version 1.9][]
;;   * 2013-03-24: [Version 2.0][]
;;   * 2016-01-09: [Version 2.1][]
;;
;; [Version 1.1]: http://jblevins.org/projects/markdown-mode/rev-1-1
;; [Version 1.2]: http://jblevins.org/projects/markdown-mode/rev-1-2
;; [Version 1.3]: http://jblevins.org/projects/markdown-mode/rev-1-3
;; [Version 1.4]: http://jblevins.org/projects/markdown-mode/rev-1-4
;; [Version 1.5]: http://jblevins.org/projects/markdown-mode/rev-1-5
;; [Version 1.6]: http://jblevins.org/projects/markdown-mode/rev-1-6
;; [Version 1.7]: http://jblevins.org/projects/markdown-mode/rev-1-7
;; [Version 1.8]: http://jblevins.org/projects/markdown-mode/rev-1-8
;; [Version 1.8.1]: http://jblevins.org/projects/markdown-mode/rev-1-8-1
;; [Version 1.9]: http://jblevins.org/projects/markdown-mode/rev-1-9
;; [Version 2.0]: http://jblevins.org/projects/markdown-mode/rev-2-0
;; [Version 2.1]: http://jblevins.org/projects/markdown-mode/rev-2-1

\f
;;; Code:

(require 'easymenu)
(require 'outline)
(require 'thingatpt)
(require 'cl-lib)
(require 'url-parse)

(defvar jit-lock-start)
(defvar jit-lock-end)

(declare-function eww-open-file "eww")
(declare-function url-path-and-query "url-parse")

\f
;;; Constants =================================================================

(defconst markdown-mode-version "2.1"
  "Markdown mode version number.")

(defconst markdown-output-buffer-name "*markdown-output*"
  "Name of temporary buffer for markdown command output.")

\f
;;; Global Variables ==========================================================

(defvar markdown-reference-label-history nil
  "History of used reference labels.")

(defvar markdown-live-preview-mode nil
  "Sentinel variable for command `markdown-live-preview-mode'.")

(defvar markdown-gfm-language-history nil
  "History list of languages used in the current buffer in GFM code blocks.")

\f
;;; Customizable Variables ====================================================

(defvar markdown-mode-hook nil
  "Hook run when entering Markdown mode.")

(defvar markdown-before-export-hook nil
  "Hook run before running Markdown to export XHTML output.
The hook may modify the buffer, which will be restored to it's
original state after exporting is complete.")

(defvar markdown-after-export-hook nil
  "Hook run after XHTML output has been saved.
Any changes to the output buffer made by this hook will be saved.")

(defgroup markdown nil
  "Major mode for editing text files in Markdown format."
  :prefix "markdown-"
  :group 'wp
  :link '(url-link "http://jblevins.org/projects/markdown-mode/"))

(defcustom markdown-command "markdown"
  "Command to run markdown."
  :group 'markdown
  :type 'string)

(defcustom markdown-command-needs-filename nil
  "Set to non-nil if `markdown-command' does not accept input from stdin.
Instead, it will be passed a filename as the final command line
option.  As a result, you will only be able to run Markdown from
buffers which are visiting a file."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-open-command nil
  "Command used for opening Markdown files directly.
For example, a standalone Markdown previewer.  This command will
be called with a single argument: the filename of the current
buffer."
  :group 'markdown
  :type 'string)

(defcustom markdown-hr-strings
  '("-------------------------------------------------------------------------------"
    "* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *"
    "---------------------------------------"
    "* * * * * * * * * * * * * * * * * * * *"
    "---------"
    "* * * * *")
  "Strings to use when inserting horizontal rules.
The first string in the list will be the default when inserting a
horizontal rule.  Strings should be listed in decreasing order of
prominence (as in headings from level one to six) for use with
promotion and demotion functions."
  :group 'markdown
  :type 'list)

(defcustom markdown-bold-underscore nil
  "Use two underscores when inserting bold text instead of two asterisks."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-italic-underscore nil
  "Use underscores when inserting italic text instead of asterisks."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-asymmetric-header nil
  "Determines if atx header style will be asymmetric.
Set to a non-nil value to use asymmetric header styling, placing
header markup only at the beginning of the line. By default,
balanced markup will be inserted at the beginning and end of the
line around the header title."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-indent-function 'markdown-indent-line
  "Function to use to indent."
  :group 'markdown
  :type 'function)

(defcustom markdown-indent-on-enter t
  "Indent new lines and continue lists when enter is pressed.
When this variable is set to t, pressing RET will call
`newline-and-indent' and will continue a list.  When set to nil,
define RET to call `newline' as usual.  In the latter case, you
can still use auto-indentation by pressing
\\[newline-and-indent] or continue lists with
\\[markdown-insert-list-item]."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-enable-wiki-links nil
  "Syntax highlighting for wiki links.
Set this to a non-nil value to turn on wiki link support by default.
Support can be toggled later using the `markdown-toggle-wiki-links'
function or \\[markdown-toggle-wiki-links]."
  :group 'markdown
  :type 'boolean
  :safe 'booleanp)

(defcustom markdown-wiki-link-alias-first t
  "When non-nil, treat aliased wiki links like [[alias text|PageName]].
Otherwise, they will be treated as [[PageName|alias text]]."
  :group 'markdown
  :type 'boolean
  :safe 'booleanp)

(defcustom markdown-wiki-link-search-subdirectories nil
  "When non-nil, search for wiki link targets in subdirectories.
This is the default search behavior for GitHub and is
automatically set to t in `gfm-mode'."
  :group 'markdown
  :type 'boolean
  :safe 'booleanp)

(defcustom markdown-wiki-link-search-parent-directories nil
  "When non-nil, search for wiki link targets in parent directories.
This is the default search behavior of Ikiwiki."
  :group 'markdown
  :type 'boolean
  :safe 'booleanp)

(defcustom markdown-wiki-link-fontify-missing nil
  "When non-nil, change wiki link face according to existence of target files.
This is expensive because it requires checking for the file each time the buffer
changes or the user switches windows.  It is disabled by default because it may
cause lag when typing on slower machines."
  :group 'markdown
  :type 'boolean
  :safe 'booleanp)

(defcustom markdown-uri-types
  '("acap" "cid" "data" "dav" "fax" "file" "ftp" "gopher" "http" "https"
    "imap" "ldap" "mailto" "mid" "modem" "news" "nfs" "nntp" "pop" "prospero"
    "rtsp" "service" "sip" "tel" "telnet" "tip" "urn" "vemmi" "wais")
  "Link types for syntax highlighting of URIs."
  :group 'markdown
  :type 'list)

(defcustom markdown-enable-math nil
  "Syntax highlighting for inline LaTeX and itex expressions.
Set this to a non-nil value to turn on math support by default.
Math support can be enabled, disabled, or toggled later using
`markdown-toggle-math' or \\[markdown-toggle-math]."
  :group 'markdown
  :type 'boolean
  :safe 'booleanp)

(defcustom markdown-css-paths nil
  "URL of CSS file to link to in the output XHTML."
  :group 'markdown
  :type 'list)

(defcustom markdown-content-type ""
  "Content type string for the http-equiv header in XHTML output.
When set to a non-empty string, insert the http-equiv attribute.
Otherwise, this attribute is omitted."
  :group 'markdown
  :type 'string)

(defcustom markdown-coding-system nil
  "Character set string for the http-equiv header in XHTML output.
Defaults to `buffer-file-coding-system' (and falling back to
`iso-8859-1' when not available).  Common settings are `utf-8'
and `iso-latin-1'.  Use `list-coding-systems' for more choices."
  :group 'markdown
  :type 'coding-system)

(defcustom markdown-xhtml-header-content ""
  "Additional content to include in the XHTML <head> block."
  :group 'markdown
  :type 'string)

(defcustom markdown-xhtml-standalone-regexp
  "^\\(<\\?xml\\|<!DOCTYPE\\|<html\\)"
  "Regexp indicating whether `markdown-command' output is standalone XHTML."
  :group 'markdown
  :type 'regexp)

(defcustom markdown-link-space-sub-char "_"
  "Character to use instead of spaces when mapping wiki links to filenames."
  :group 'markdown
  :type 'string)

(defcustom markdown-reference-location 'header
  "Position where new reference definitions are inserted in the document."
  :group 'markdown
  :type '(choice (const :tag "At the end of the document" end)
                 (const :tag "Immediately after the current block" immediately)
                 (const :tag "Before next header" header)))

(defcustom markdown-footnote-location 'end
  "Position where new footnotes are inserted in the document."
  :group 'markdown
  :type '(choice (const :tag "At the end of the document" end)
                 (const :tag "Immediately after the current block" immediately)
                 (const :tag "Before next header" header)))

(defcustom markdown-unordered-list-item-prefix "  * "
  "String inserted before unordered list items."
  :group 'markdown
  :type 'string)

(defcustom markdown-nested-imenu-heading-index nil
  "Use nested or flat imenu heading index.
A nested index may provide more natural browsing from the menu,
but a flat list may allow for faster keyboard navigation via tab
completion."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-make-gfm-checkboxes-buttons t
  "When non-nil, make GFM checkboxes into buttons."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-use-pandoc-style-yaml-metadata nil
  "When non-nil, allow yaml metadata anywhere in the document."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-split-window-direction 'any
  "Preference for splitting windows for static and live preview.
The default value is 'any, which instructs Emacs to use
`split-window-sensibly' to automatically choose how to split
windows based on the values of `split-width-threshold' and
`split-height-threshold' and the available windows.  To force
vertically split (left and right) windows, set this to 'vertical
or 'right.  To force horizontally split (top and bottom) windows,
set this to 'horizontal or 'below."
  :group 'markdown
  :type 'symbol)

(defcustom markdown-live-preview-window-function
  'markdown-live-preview-window-eww
  "Function to display preview of Markdown output within Emacs.
Function must update the buffer containing the preview and return
the buffer."
  :group 'markdown
  :type 'function)

(defcustom markdown-live-preview-delete-export 'delete-on-destroy
  "Delete exported html file when using `markdown-live-preview-export'.
If set to 'delete-on-export, delete on every export. When set to
'delete-on-destroy delete when quitting from command
`markdown-live-preview-mode'. Never delete if set to nil."
  :group 'markdown
  :type 'symbol)

(defcustom markdown-list-indent-width 4
  "Depth of indentation for markdown lists.
Used in `markdown-demote-list-item' and
`markdown-promote-list-item'."
  :group 'markdown
  :type 'integer)

(defcustom markdown-gfm-additional-languages nil
  "Extra languages made available when inserting GFM code blocks.
Language strings must have be trimmed of whitespace and not
contain any curly braces. They may be of arbitrary
capitalization, though."
  :group 'markdown
  :type '(repeat (string :validate markdown-validate-language-string)))

(defcustom markdown-gfm-use-electric-backquote t
  "Use `markdown-electric-backquote' when backquote is hit three times."
  :group 'markdown
  :type 'boolean)

(defcustom markdown-gfm-downcase-languages t
  "If non-nil, downcase suggested languages.
This applies to insertions done with
`markdown-electric-backquote'."
  :group 'markdown
  :type 'boolean)

\f
;;; Regular Expressions =======================================================

(defconst markdown-regex-comment-start
  "<!--"
  "Regular expression matches HTML comment opening.")

(defconst markdown-regex-comment-end
  "--[ \t]*>"
  "Regular expression matches HTML comment closing.")

(defconst markdown-regex-link-inline
  "\\(!\\)?\\(\\[\\)\\([^]^][^]]*\\|\\)\\(\\]\\)\\((\\)\\([^)]*?\\)\\(?:\\s-+\\(\"[^\"]*\"\\)\\)?\\()\\)"
  "Regular expression for a [text](file) or an image link ![text](file).
Group 1 matches the leading exclamation point (optional).
Group 2 matches the opening square bracket.
Group 3 matches the text inside the square brackets.
Group 4 matches the closing square bracket.
Group 5 matches the opening parenthesis.
Group 6 matches the URL.
Group 7 matches the title (optional).
Group 8 matches the closing parenthesis.")

(defconst markdown-regex-link-reference
  "\\(!\\)?\\(\\[\\)\\([^]^][^]]*\\|\\)\\(\\]\\)[ ]?\\(\\[\\)\\([^]]*?\\)\\(\\]\\)"
  "Regular expression for a reference link [text][id].
Group 1 matches the leading exclamation point (optional).
Group 2 matches the opening square bracket for the link text.
Group 3 matches the text inside the square brackets.
Group 4 matches the closing square bracket for the link text.
Group 5 matches the opening square bracket for the reference label.
Group 6 matches the reference label.
Group 7 matches the closing square bracket for the reference label.")

(defconst markdown-regex-reference-definition
  "^ \\{0,3\\}\\(\\[\\)\\([^]\n]+?\\)\\(\\]\\)\\(:\\)\\s *\\(.*?\\)\\s *\\( \"[^\"]*\"$\\|$\\)"
  "Regular expression for a reference definition.
Group 1 matches the opening square bracket.
Group 2 matches the reference label.
Group 3 matches the closing square bracket.
Group 4 matches the colon.
Group 5 matches the URL.
Group 6 matches the title attribute (optional).")

(defconst markdown-regex-footnote
  "\\(\\[\\^\\)\\(.+?\\)\\(\\]\\)"
  "Regular expression for a footnote marker [^fn].
Group 1 matches the opening square bracket and carat.
Group 2 matches only the label, without the surrounding markup.
Group 3 matches the closing square bracket.")

(defconst markdown-regex-header
  "^\\(?:\\([^\r\n\t -].*\\)\n\\(?:\\(=+\\)\\|\\(-+\\)\\)\\|\\(#+\\)[ \t]+\\(.*?\\)[ \t]*\\(#*\\)\\)$"
  "Regexp identifying Markdown headings.
Group 1 matches the text of a setext heading.
Group 2 matches the underline of a level-1 setext heading.
Group 3 matches the underline of a level-2 setext heading.
Group 4 matches the opening hash marks of an atx heading.
Group 5 matches the text, without surrounding whitespace, of an atx heading.
Group 6 matches the closing hash marks of an atx heading.")

(defconst markdown-regex-header-setext
  "^\\([^\r\n\t -].*\\)\n\\(=+\\|-+\\)$"
  "Regular expression for generic setext-style (underline) headers.")

(defconst markdown-regex-header-atx
  "^\\(#+\\)[ \t]+\\(.*?\\)[ \t]*\\(#*\\)$"
  "Regular expression for generic atx-style (hash mark) headers.")

(defconst markdown-regex-hr
  "^\\(\\*[ ]?\\*[ ]?\\*[ ]?[\\* ]*\\|-[ ]?-[ ]?-[--- ]*\\)$"
  "Regular expression for matching Markdown horizontal rules.")

(defconst markdown-regex-code
  "\\(?:\\`\\|[^\\]\\)\\(\\(`+\\)\\(\\(?:.\\|\n[^\n]\\)*?[^`]\\)\\(\\2\\)\\)\\(?:[^`]\\|\\'\\)"
  "Regular expression for matching inline code fragments.

Group 1 matches the entire code fragment including the backticks.
Group 2 matches the opening backticks.
Group 3 matches the code fragment itself, without backticks.
Group 4 matches the closing backticks.

The leading, unnumbered group ensures that the leading backquote
character is not escaped.
The last group, also unnumbered, requires that the character
following the code fragment is not a backquote.
Note that \\(?:.\\|\n[^\n]\\) matches any character, including newlines,
but not two newlines in a row.")

(defconst markdown-regex-kbd
  "\\(<kbd>\\)\\(\\(?:.\\|\n[^\n]\\)*?\\)\\(</kbd>\\)"
  "Regular expression for matching <kbd> tags.
Groups 1 and 3 match the opening and closing tags.
Group 2 matches the key sequence.")

(defconst markdown-regex-gfm-code-block-open
 "^[[:blank:]]*\\(```\\)[ ]?\\([^[:space:]]+\\|{[^}]*}\\)?\\([[:space:]]*?\\)$"
 "Regular expression matching opening of GFM code blocks.
Group 1 matches the opening three backticks.
Group 2 matches the language identifier (optional).")

(defconst markdown-regex-gfm-code-block-close
 "^[[:blank:]]*\\(```\\)\\s *?$"
 "Regular expression matching closing of GFM code blocks.
Group 1 matches the closing three backticks.")

(defconst markdown-regex-pre
  "^\\(    \\|\t\\).*$"
  "Regular expression for matching preformatted text sections.")

(defconst markdown-regex-list
  "^\\([ \t]*\\)\\([0-9#]+\\.\\|[\\*\\+:-]\\)\\([ \t]+\\)"
  "Regular expression for matching list items.")

(defconst markdown-regex-bold
  "\\(^\\|[^\\]\\)\\(\\([*_]\\{2\\}\\)\\([^ \n\t\\]\\|[^ \n\t]\\(?:.\\|\n[^\n]\\)*?[^\\ ]\\)\\(\\3\\)\\)"
  "Regular expression for matching bold text.
Group 1 matches the character before the opening asterisk or
underscore, if any, ensuring that it is not a backslash escape.
Group 2 matches the entire expression, including delimiters.
Groups 3 and 5 matches the opening and closing delimiters.
Group 4 matches the text inside the delimiters.")

(defconst markdown-regex-italic
  "\\(?:^\\|[^\\]\\)\\(\\([*_]\\)\\([^ \n\t\\]\\|[^ \n\t]\\(?:.\\|\n[^\n]\\)*?[^\\ ]\\)\\(\\2\\)\\)"
  "Regular expression for matching italic text.
The leading unnumbered matches the character before the opening
asterisk or underscore, if any, ensuring that it is not a
backslash escape.
Group 1 matches the entire expression, including delimiters.
Groups 2 and 4 matches the opening and closing delimiters.
Group 3 matches the text inside the delimiters.")

(defconst markdown-regex-strike-through
  "\\(^\\|[^\\]\\)\\(\\(~~\\)\\([^ \n\t\\]\\|[^ \n\t]\\(?:.\\|\n[^\n]\\)*?[^\\ ]\\)\\(~~\\)\\)"
  "Regular expression for matching strike-through text.
Group 1 matches the character before the opening tilde, if any,
ensuring that it is not a backslash escape.
Group 2 matches the entire expression, including delimiters.
Groups 3 and 5 matches the opening and closing delimiters.
Group 4 matches the text inside the delimiters.")

(defconst markdown-regex-gfm-italic
  "\\(?:^\\|\\s-\\)\\(\\([*_]\\)\\([^ \\]\\2\\|[^ ]\\(?:.\\|\n[^\n]\\)*?[^\\ ]\\)\\(\\2\\)\\)"
  "Regular expression for matching italic text in GitHub Flavored Markdown.
Underscores in words are not treated as special.
Group 1 matches the entire expression, including delimiters.
Groups 2 and 4 matches the opening and closing delimiters.
Group 3 matches the text inside the delimiters.")

(defconst markdown-regex-blockquote
  "^[ \t]*\\(>\\)\\(.*\\)$"
  "Regular expression for matching blockquote lines.
Group 1 matches the leading angle bracket.
Group 2 matches the text.")

(defconst markdown-regex-line-break
  "[^ \n\t][ \t]*\\(  \\)$"
  "Regular expression for matching line breaks.")

(defconst markdown-regex-wiki-link
  "\\(?:^\\|[^\\]\\)\\(\\(\\[\\[\\)\\([^]|]+\\)\\(?:\\(|\\)\\([^]]+\\)\\)?\\(\\]\\]\\)\\)"
  "Regular expression for matching wiki links.
This matches typical bracketed [[WikiLinks]] as well as 'aliased'
wiki links of the form [[PageName|link text]].
The meanings of the first and second components depend
on the value of `markdown-wiki-link-alias-first'.

Group 1 matches the entire link.
Group 2 matches the opening square brackets.
Group 3 matches the first component of the wiki link.
Group 4 matches the pipe separator, when present.
Group 5 matches the second component of the wiki link, when present.
Group 6 matches the closing square brackets.")

(defconst markdown-regex-uri
  (concat (regexp-opt markdown-uri-types) ":[^]\t\n\r<>,;() ]+")
  "Regular expression for matching inline URIs.")

(defconst markdown-regex-angle-uri
  (concat "\\(<\\)\\(" (regexp-opt markdown-uri-types) ":[^]\t\n\r<>,;()]+\\)\\(>\\)")
  "Regular expression for matching inline URIs in angle brackets.")

(defconst markdown-regex-email
  "<\\(\\(\\sw\\|\\s_\\|\\s.\\)+@\\(\\sw\\|\\s_\\|\\s.\\)+\\)>"
  "Regular expression for matching inline email addresses.")

(defsubst markdown-make-regex-link-generic ()
  "Make regular expression for matching any recognized link."
  (concat "\\(?:" markdown-regex-link-inline
          (when markdown-enable-wiki-links
            (concat "\\|" markdown-regex-wiki-link))
          "\\|" markdown-regex-link-reference
          "\\|" markdown-regex-angle-uri "\\)"))

(defconst markdown-regex-gfm-checkbox
  " \\(\\[[ xX]\\]\\) "
  "Regular expression for matching GFM checkboxes.
Group 1 matches the text to become a button.")

(defconst markdown-regex-block-separator
  "\\(\\`\\|\\(\n[ \t]*\n\\)[^\n \t]\\)"
  "Regular expression for matching block boundaries.")

(defconst markdown-regex-math-inline-single
  "\\(?:^\\|[^\\]\\)\\(\\$\\)\\(\\(?:[^\\$]\\|\\\\.\\)*\\)\\(\\$\\)"
  "Regular expression for itex $..$ math mode expressions.
Groups 1 and 3 match the opening and closing dollar signs.
Group 3 matches the mathematical expression contained within.")

(defconst markdown-regex-math-inline-double
  "\\(?:^\\|[^\\]\\)\\(\\$\\$\\)\\(\\(?:[^\\$]\\|\\\\.\\)*\\)\\(\\$\\$\\)"
  "Regular expression for itex $$..$$ math mode expressions.
Groups 1 and 3 match opening and closing dollar signs.
Group 3 matches the mathematical expression contained within.")

(defconst markdown-regex-math-display
  "^\\(\\\\\\[\\)\\(\\(?:.\\|\n\\)*?\\)?\\(\\\\\\]\\)$"
  "Regular expression for itex \[..\] display mode expressions.
Groups 1 and 3 match the opening and closing delimiters.
Group 2 matches the mathematical expression contained within.")

(defsubst markdown-make-tilde-fence-regex (num-tildes &optional end-of-line)
  "Return regexp matching a Pandoc code fence at least NUM-TILDES long.
END-OF-LINE is the regexp construct to indicate end of line; $ if
missing."
  (format "%s%d%s%s" "^\\([~]\\{" num-tildes ",\\}\\)" (or end-of-line "$")))

(defconst markdown-regex-tilde-fence-begin
  (markdown-make-tilde-fence-regex
   3 "[ ]?\\([^[:space:]]+\\|{[^}]*}\\)?\\([[:space:]]*?\\)$")
  "Regular expression for matching Pandoc tildes.")

(defconst markdown-regex-declarative-metadata
  "^\\([[:alpha:]][[:alpha:] _-]*?\\)\\([:=][ \t]*\\)\\(.*\\)$"
  "Regular expression for matching declarative metadata statements.
This matches MultiMarkdown metadata as well as YAML and TOML
assignments such as the following:

    variable: value

or

    variable = value")

(defconst markdown-regex-pandoc-metadata
  "^\\(%\\)\\([ \t]*\\)\\(.*\\(?:\n[ \t]+.*\\)*\\)"
  "Regular expression for matching Pandoc metadata.")

(defconst markdown-regex-yaml-metadata-border
  "\\(-\\{3\\}\\)$"
  "Regular expression for matching yaml metadata.")

(defconst markdown-regex-yaml-pandoc-metadata-end-border
  "^\\(\\.\\{3\\}\\|\\-\\{3\\}\\)$"
  "Regular expression for matching yaml metadata end borders.")

(defsubst markdown-get-yaml-metadata-start-border ()
  "Return yaml metadata start border depending upon whether Pandoc is used."
  (concat
   (if markdown-use-pandoc-style-yaml-metadata "^" "\\`")
   markdown-regex-yaml-metadata-border))

(defsubst markdown-get-yaml-metadata-end-border (_)
  "Return yaml metadata end border depending upon whether Pandoc is used."
  (if markdown-use-pandoc-style-yaml-metadata
      markdown-regex-yaml-pandoc-metadata-end-border
    markdown-regex-yaml-metadata-border))

\f
;;; Syntax ====================================================================

(defun markdown-syntax-propertize-extend-region (start end)
  "Extend START to END region to include an entire block of text.
This helps improve syntax analysis for block constructs.
Returns a cons (NEW-START . NEW-END) or nil if no adjustment should be made.
Function is called repeatedly until it returns nil. For details, see
`syntax-propertize-extend-region-functions'."
  (save-match-data
    (save-excursion
      (let* ((new-start (progn (goto-char start)
                               (skip-chars-forward "\n")
                               (if (re-search-backward "\n\n" nil t)
                                   (min start (match-end 0))
                                 (point-min))))
             (new-end (progn (goto-char end)
                             (skip-chars-backward "\n")
                             (if (re-search-forward "\n\n" nil t)
                                 (max end (match-beginning 0))
                               (point-max))))
             (code-match (markdown-code-block-at-pos new-start))
             (new-start (or (and code-match (cl-first code-match)) new-start))
             (code-match (markdown-code-block-at-pos end))
             (new-end (or (and code-match (cl-second code-match)) new-end)))
        (unless (and (eq new-start start) (eq new-end end))
          (cons new-start (min new-end (point-max))))))))

(defun markdown-font-lock-extend-region-function (start end _)
  "Used in `jit-lock-after-change-extend-region-functions'.
Delegates to `markdown-syntax-propertize-extend-region'. START
and END are the previous region to refontify."
  (let ((res (markdown-syntax-propertize-extend-region start end)))
    (when res
      (setq jit-lock-start (car res)
            jit-lock-end (cdr res)))))

(defun markdown-syntax-propertize-pre-blocks (start end)
  "Match preformatted text blocks from START to END."
  (save-excursion
    (goto-char start)
    (let ((levels (markdown-calculate-list-levels))
          indent pre-regexp close-regexp open close)
      (while (and (< (point) end) (not close))
        ;; Search for a region with sufficient indentation
        (if (null levels)
            (setq indent 1)
          (setq indent (1+ (length levels))))
        (setq pre-regexp (format "^\\(    \\|\t\\)\\{%d\\}" indent))
        (setq close-regexp (format "^\\(    \\|\t\\)\\{0,%d\\}\\([^ \t]\\)" (1- indent)))

        (cond
         ;; If not at the beginning of a line, move forward
         ((not (bolp)) (forward-line))
         ;; Move past blank lines
         ((markdown-cur-line-blank-p) (forward-line))
         ;; At headers and horizontal rules, reset levels
         ((markdown-new-baseline-p) (forward-line) (setq levels nil))
         ;; If the current line has sufficient indentation, mark out pre block
         ;; The opening should be preceded by a blank line.
         ((and (looking-at pre-regexp)
               (save-match-data (markdown-prev-line-blank-p)))
          (setq open (match-beginning 0))
          (while (and (or (looking-at-p pre-regexp) (markdown-cur-line-blank-p))
                      (not (eobp)))
            (forward-line))
          (skip-syntax-backward "-")
          (setq close (point)))
         ;; If current line has a list marker, update levels, move to end of block
         ((looking-at markdown-regex-list)
          (setq levels (markdown-update-list-levels
                        (match-string 2) (current-indentation) levels))
          (markdown-end-of-block-element))
         ;; If this is the end of the indentation level, adjust levels accordingly.
         ;; Only match end of indentation level if levels is not the empty list.
         ((and (car levels) (looking-at-p close-regexp))
          (setq levels (markdown-update-list-levels
                        nil (current-indentation) levels))
          (markdown-end-of-block-element))
         (t (markdown-end-of-block-element))))

      (when (and open close)
        ;; Set text property data
        (put-text-property open close 'markdown-pre (list open close))
        ;; Recursively search again
        (markdown-syntax-propertize-pre-blocks (point) end)))))

(defconst markdown-fenced-block-pairs
  `(((,markdown-regex-tilde-fence-begin markdown-tilde-fence-begin)
     (markdown-make-tilde-fence-regex markdown-tilde-fence-end)
     markdown-fenced-code)
    ((markdown-get-yaml-metadata-start-border markdown-yaml-metadata-begin)
     (markdown-get-yaml-metadata-end-border markdown-yaml-metadata-end)
     markdown-yaml-metadata-section)
    ((,markdown-regex-gfm-code-block-open markdown-gfm-block-begin)
     (,markdown-regex-gfm-code-block-close markdown-gfm-block-end)
     markdown-gfm-code))
  "Mapping of regular expressions to \"fenced-block\" constructs.
These constructs are distinguished by having a distinctive start
and end pattern, both of which take up an entire line of text,
but no special pattern to identify text within the fenced
blocks (unlike blockquotes and indented-code sections).

Each element within this list takes the form:

  ((START-REGEX-OR-FUN START-PROPERTY)
   (END-REGEX-OR-FUN END-PROPERTY)
   MIDDLE-PROPERTY)

Each *-REGEX-OR-FUN element can be a regular expression as a string, or a
function which evaluates to same. Functions for START-REGEX-OR-FUN accept no
arguments, but functions for END-REGEX-OR-FUN accept a single numerical argument
which is the length of the first group of the START-REGEX-OR-FUN match, which
can be ignored if unnecessary. `markdown-maybe-funcall-regexp' is used to
evaluate these into \"real\" regexps.

The *-PROPERTY elements are the text properties applied to each part of the
block construct when it is matched using
`markdown-syntax-propertize-fenced-block-constructs'. START-PROPERTY is applied
to the text matching START-REGEX-OR-FUN, END-PROPERTY to END-REGEX-OR-FUN, and
MIDDLE-PROPERTY to the text in between the two. The value of *-PROPERTY is the
`match-data' when the regexp was matched to the text. In the case of
MIDDLE-PROPERTY, the value is a false match data of the form '(begin end), with
begin and end set to the edges of the \"middle\" text. This makes fontification
easier.")

(defun markdown-text-property-at-point (prop)
  (get-text-property (point) prop))

(defsubst markdown-maybe-funcall-regexp (object &optional arg)
  (cond ((functionp object)
         (if arg (funcall object arg) (funcall object)))
        ((stringp object) object)
        (t (error "Object cannot be turned into regex"))))

(defsubst markdown-get-start-fence-regexp ()
  "Return regexp to find all \"start\" sections of fenced block constructs.
Which construct is actually contained in the match must be found separately."
  (mapconcat
   #'identity
   ;; FIXME: Why `cl-mapcar' rather than `mapcar'?
   (cl-mapcar (lambda (entry) (markdown-maybe-funcall-regexp (caar entry)))
              markdown-fenced-block-pairs)
   "\\|"))

(defun markdown-get-fenced-block-begin-properties ()
  (cl-mapcar (lambda (entry) (cl-cadar entry)) markdown-fenced-block-pairs))

(defun markdown-get-fenced-block-end-properties ()
  (cl-mapcar (lambda (entry) (cl-cadadr entry)) markdown-fenced-block-pairs))

(defun markdown-get-fenced-block-middle-properties ()
  (cl-mapcar #'cl-third markdown-fenced-block-pairs))

(defun markdown-find-previous-prop (prop &optional lim)
  "Find previous place where property PROP is non-nil, up to LIM.
Return a cons of (pos . property). pos is point if point contains
non-nil PROP."
  (let ((res
         (if (get-text-property (point) prop) (point)
           (previous-single-property-change
            (point) prop nil (or lim (point-min))))))
    (when (and (not (get-text-property res prop))
               (> res (point-min))
               (get-text-property (1- res) prop))
      (cl-decf res))
    (when (and res (get-text-property res prop)) (cons res prop))))

(defun markdown-find-next-prop (prop &optional lim)
  "Find next place where property PROP is non-nil, up to LIM.
Return a cons of (POS . PROPERTY) where POS is point if point
contains non-nil PROP."
  (let ((res
         (if (get-text-property (point) prop) (point)
           (next-single-property-change
            (point) prop nil (or lim (point-max))))))
    (when (and res (get-text-property res prop)) (cons res prop))))

(defun markdown-min-of-seq (map-fn seq)
  "Apply MAP-FN to SEQ and return element of SEQ with minimum value of MAP-FN."
  (cl-loop for el in seq
           with min = 1.0e+INF          ; infinity
           with min-el = nil
           do (let ((res (funcall map-fn el)))
                (when (< res min)
                  (setq min res)
                  (setq min-el el)))
           finally return min-el))

(defun markdown-find-previous-block ()
  "Find previous block.
Detect whether `markdown-syntax-propertize-fenced-block-constructs' was
unable to propertize the entire block, but was able to propertize the beginning
of the block. If so, return a cons of (pos . property) where the beginning of
the block was propertized."
  (let ((start-pt (point))
        (closest-open
         (markdown-min-of-seq
          #'car
          (cl-remove-if
           #'null
           (cl-mapcar
            #'markdown-find-previous-prop
            (markdown-get-fenced-block-begin-properties))))))
    (when closest-open
      (let* ((length-of-open-match
              (let ((match-d
                     (get-text-property (car closest-open) (cdr closest-open))))
                (- (cl-fourth match-d) (cl-third match-d))))
             (end-regexp
              (markdown-maybe-funcall-regexp
               (cl-caadr
                (cl-find-if
                 (lambda (entry) (eq (cl-cadar entry) (cdr closest-open)))
                 markdown-fenced-block-pairs))
               length-of-open-match))
             (end-prop-loc
              (save-excursion
                (save-match-data
                  (goto-char (car closest-open))
                  (and (re-search-forward end-regexp start-pt t)
                       (match-beginning 0))))))
        (and (not end-prop-loc) closest-open)))))

(defun markdown-get-fenced-block-from-start (prop)
  "Return limits of an enclosing fenced block from its start, using PROP.
Return value is a list usable as `match-data'."
  (catch 'no-rest-of-block
    (let* ((correct-entry
            (cl-find-if
             (lambda (entry) (eq (cl-cadar entry) prop))
             markdown-fenced-block-pairs))
           (begin-of-begin (cl-first (markdown-text-property-at-point prop)))
           (middle-prop (cl-third correct-entry))
           (end-prop (cl-cadadr correct-entry))
           (end-of-end
            (save-excursion
              (goto-char (match-end 0))   ; end of begin
              (unless (eobp) (forward-char))
              (let ((mid-prop-v (markdown-text-property-at-point middle-prop)))
                (if (not mid-prop-v)    ; no middle
                    (progn
                      ;; try to find end by advancing one
                      (let ((end-prop-v
                             (markdown-text-property-at-point end-prop)))
                        (if end-prop-v (cl-second end-prop-v)
                          (throw 'no-rest-of-block nil))))
                  (set-match-data mid-prop-v)
                  (goto-char (match-end 0))   ; end of middle
                  (beginning-of-line)         ; into end
                  (cl-second (markdown-text-property-at-point end-prop)))))))
      (list begin-of-begin end-of-end))))

(defun markdown-get-fenced-block-from-middle (prop)
  "Return limits of an enclosing fenced block from its middle, using PROP.
Return value is a list usable as `match-data'."
  (let* ((correct-entry
          (cl-find-if
           (lambda (entry) (eq (cl-third entry) prop))
           markdown-fenced-block-pairs))
         (begin-prop (cl-cadar correct-entry))
         (begin-of-begin
          (save-excursion
            (goto-char (match-beginning 0))
            (unless (bobp) (forward-line -1))
            (beginning-of-line)
            (cl-first (markdown-text-property-at-point begin-prop))))
         (end-prop (cl-cadadr correct-entry))
         (end-of-end
          (save-excursion
            (goto-char (match-end 0))
            (beginning-of-line)
            (cl-second (markdown-text-property-at-point end-prop)))))
    (list begin-of-begin end-of-end)))

(defun markdown-get-fenced-block-from-end (prop)
  "Return limits of an enclosing fenced block from its end, using PROP.
Return value is a list usable as `match-data'."
  (let* ((correct-entry
          (cl-find-if
           (lambda (entry) (eq (cl-cadadr entry) prop))
           markdown-fenced-block-pairs))
         (end-of-end (cl-second (markdown-text-property-at-point prop)))
         (middle-prop (cl-third correct-entry))
         (begin-prop (cl-cadar correct-entry))
         (begin-of-begin
          (save-excursion
            (goto-char (match-beginning 0)) ; beginning of end
            (unless (bobp) (backward-char)) ; into middle
            (let ((mid-prop-v (markdown-text-property-at-point middle-prop)))
              (if (not mid-prop-v)
                  (progn
                    (beginning-of-line)
                    (cl-first (markdown-text-property-at-point begin-prop)))
                (set-match-data mid-prop-v)
                (goto-char (match-beginning 0))   ; beginning of middle
                (unless (bobp) (forward-line -1)) ; into beginning
                (beginning-of-line)
                (cl-first (markdown-text-property-at-point begin-prop)))))))
    (list begin-of-begin end-of-end)))

(defun markdown-get-enclosing-fenced-block-construct (&optional pos)
  "Get \"fake\" match data for block enclosing POS.
Returns fake match data which encloses the start, middle, and end
of the block construct enclosing POS, if it exists. Used in
`markdown-code-block-at-pos'."
  (save-excursion
    (when pos (goto-char pos))
    (beginning-of-line)
    (car
     (cl-remove-if
      #'null
      (cl-mapcar
       (lambda (fun-and-prop)
         (cl-destructuring-bind (fun prop) fun-and-prop
           (when prop
             (save-match-data
               (set-match-data (markdown-text-property-at-point prop))
               (funcall fun prop)))))
       `((markdown-get-fenced-block-from-start
          ,(cl-find-if
            #'markdown-text-property-at-point
            (markdown-get-fenced-block-begin-properties)))
         (markdown-get-fenced-block-from-middle
          ,(cl-find-if
            #'markdown-text-property-at-point
            (markdown-get-fenced-block-middle-properties)))
         (markdown-get-fenced-block-from-end
          ,(cl-find-if
            #'markdown-text-property-at-point
            (markdown-get-fenced-block-end-properties)))))))))

(defun markdown-propertize-end-match (reg end correct-entry enclosed-text-start)
  "Get match for REG up to END, if exists, and propertize appropriately.
CORRECT-ENTRY is an entry in `markdown-fenced-block-pairs' and
ENCLOSED-TEXT-START is the start of the \"middle\" section of the block."
  (when (re-search-forward reg end t)
    (put-text-property (match-beginning 0) (match-end 0)
                       (cl-cadadr correct-entry) (match-data t))
    (put-text-property
     enclosed-text-start (match-beginning 0) (cl-third correct-entry)
     (list enclosed-text-start (match-beginning 0)))))

(defun markdown-syntax-propertize-fenced-block-constructs (start end)
  "Propertize according to `markdown-fenced-block-pairs' from START to END.
If unable to propertize an entire block (if the start of a block is within START
and END, but the end of the block is not), propertize the start section of a
block, then in a subsequent call propertize both middle and end by finding the
start which was previously propertized."
  (let ((start-reg (markdown-get-start-fence-regexp)))
    (save-excursion
      (goto-char start)
      ;; start from previous unclosed block, if exists
      (let ((prev-begin-block (markdown-find-previous-block)))
        (when prev-begin-block
          (let* ((correct-entry
                  (cl-find-if (lambda (entry)
                                (eq (cdr prev-begin-block) (cl-cadar entry)))
                              markdown-fenced-block-pairs))
                 (enclosed-text-start (1+ (car prev-begin-block)))
                 (start-length
                  (save-excursion
                    (goto-char (car prev-begin-block))
                    (string-match
                     (markdown-maybe-funcall-regexp
                      (caar correct-entry))
                     (buffer-substring
                      (point-at-bol) (point-at-eol)))
                    (- (match-end 1) (match-beginning 1))))
                 (end-reg (markdown-maybe-funcall-regexp
                           (cl-caadr correct-entry) start-length)))
            (markdown-propertize-end-match
             end-reg end correct-entry enclosed-text-start))))
      ;; find all new blocks within region
      (while (re-search-forward start-reg end t)
        ;; we assume the opening constructs take up (only) an entire line,
        ;; so we re-check the current line
        (let* ((cur-line (buffer-substring (point-at-bol) (point-at-eol)))
               ;; find entry in `markdown-fenced-block-pairs' corresponding
               ;; to regex which was matched
               (correct-entry
                (cl-find-if
                 (lambda (fenced-pair)
                   (string-match-p
                    (markdown-maybe-funcall-regexp (caar fenced-pair))
                    cur-line))
                 markdown-fenced-block-pairs))
               (enclosed-text-start
                (save-excursion (1+ (point-at-eol))))
               (end-reg
                (markdown-maybe-funcall-regexp
                 (cl-caadr correct-entry)
                 (if (and (match-beginning 1) (match-end 1))
                     (- (match-end 1) (match-beginning 1))
                   0))))
          ;; get correct match data
          (save-excursion
            (beginning-of-line)
            (re-search-forward
             (markdown-maybe-funcall-regexp (caar correct-entry))
             (point-at-eol)))
          ;; mark starting, even if ending is outside of region
          (put-text-property (match-beginning 0) (match-end 0)
                             (cl-cadar correct-entry) (match-data t))
          (markdown-propertize-end-match
           end-reg end correct-entry enclosed-text-start))))))

(defun markdown-syntax-propertize-blockquotes (start end)
  "Match blockquotes from START to END."
  (save-excursion
    (goto-char start)
    (while (and (re-search-forward markdown-regex-blockquote end t)
                (not (markdown-code-block-at-pos (match-beginning 0))))
      (put-text-property (match-beginning 0) (match-end 0)
                         'markdown-blockquote
                         (match-data t)))))

(defun markdown-syntax-propertize-yaml-metadata (start end)
  (save-excursion
    (goto-char start)
    (cl-loop
     while (re-search-forward markdown-regex-declarative-metadata end t)
     do (when (get-text-property (match-beginning 0)
                                 'markdown-yaml-metadata-section)
          (put-text-property (match-beginning 1) (match-end 1)
                             'markdown-metadata-key (match-data t))
          (put-text-property (match-beginning 2) (match-end 2)
                             'markdown-metadata-markup (match-data t))
          (put-text-property (match-beginning 3) (match-end 3)
                             'markdown-metadata-value (match-data t))))))

(defun markdown-syntax-propertize-headings (start end)
  "Match headings of type SYMBOL with REGEX from START to END."
  (goto-char start)
  (while (re-search-forward markdown-regex-header end t)
    (unless (markdown-code-block-at-pos (match-beginning 0))
      (put-text-property
       (match-beginning 0) (match-end 0) 'markdown-heading t)
      (put-text-property
       (match-beginning 0) (match-end 0)
       (cond ((match-string-no-properties 2) 'markdown-heading-1-setext)
             ((match-string-no-properties 3) 'markdown-heading-2-setext)
             (t (let ((atx-level (length (match-string-no-properties 4))))
                  (intern (format "markdown-heading-%d-atx" atx-level)))))
       (match-data t)))))

(defun markdown-syntax-propertize-comments (start end)
  "Match HTML comments from the START to END."
  (let* ((state (syntax-ppss)) (in-comment (nth 4 state)))
    (goto-char start)
    (cond
     ;; Comment start
     ((and (not in-comment)
           (re-search-forward markdown-regex-comment-start end t)
           (not (markdown-inline-code-at-point-p))
           (not (markdown-code-block-at-point-p)))
      (let ((open-beg (match-beginning 0)))
        (put-text-property open-beg (1+ open-beg)
                           'syntax-table (string-to-syntax "<"))
        (markdown-syntax-propertize-comments
         (min (1+ (match-end 0)) end (point-max)) end)))
     ;; Comment end
     ((and in-comment
           (re-search-forward markdown-regex-comment-end end t))
      (put-text-property (1- (match-end 0)) (match-end 0)
                         'syntax-table (string-to-syntax ">"))
      (markdown-syntax-propertize-comments
       (min (1+ (match-end 0)) end (point-max)) end))
     ;; Nothing found
     (t nil))))

(defvar markdown--syntax-properties
  (list 'markdown-tilde-fence-begin nil
        'markdown-tilde-fence-end nil
        'markdown-fenced-code nil
        'markdown-yaml-metadata-begin nil
        'markdown-yaml-metadata-end nil
        'markdown-yaml-metadata-section nil
        'markdown-gfm-block-begin nil
        'markdown-gfm-block-end nil
        'markdown-gfm-code nil
        'markdown-pre nil
        'markdown-blockquote nil
        'markdown-heading nil
        'markdown-heading-1-setext nil
        'markdown-heading-2-setext nil
        'markdown-heading-1-atx nil
        'markdown-heading-2-atx nil
        'markdown-heading-3-atx nil
        'markdown-heading-4-atx nil
        'markdown-heading-5-atx nil
        'markdown-heading-6-atx nil
        'markdown-metadata-key nil
        'markdown-metadata-value nil
        'markdown-metadata-markup nil)
  "Property list of all known markdown syntactic properties.")

(defun markdown-syntax-propertize (start end)
  "Function used as `syntax-propertize-function'.
START and END delimit region to propertize."
  (remove-text-properties start end markdown--syntax-properties)
  (markdown-syntax-propertize-fenced-block-constructs start end)
  (markdown-syntax-propertize-yaml-metadata start end)
  (markdown-syntax-propertize-pre-blocks start end)
  (markdown-syntax-propertize-blockquotes start end)
  (markdown-syntax-propertize-headings start end)
  (markdown-syntax-propertize-comments start end))

\f
;;; Font Lock =================================================================

(require 'font-lock)

(defvar markdown-italic-face 'markdown-italic-face
  "Face name to use for italic text.")

(defvar markdown-bold-face 'markdown-bold-face
  "Face name to use for bold text.")

(defvar markdown-strike-through-face 'markdown-strike-through-face
  "Face name to use for strike-through text.")

(defvar markdown-header-delimiter-face 'markdown-header-delimiter-face
  "Face name to use as a base for header delimiters.")

(defvar markdown-header-rule-face 'markdown-header-rule-face
  "Face name to use as a base for header rules.")

(defvar markdown-header-face 'markdown-header-face
  "Face name to use as a base for headers.")

(defvar markdown-header-face-1 'markdown-header-face-1
  "Face name to use for level-1 headers.")

(defvar markdown-header-face-2 'markdown-header-face-2
  "Face name to use for level-2 headers.")

(defvar markdown-header-face-3 'markdown-header-face-3
  "Face name to use for level-3 headers.")

(defvar markdown-header-face-4 'markdown-header-face-4
  "Face name to use for level-4 headers.")

(defvar markdown-header-face-5 'markdown-header-face-5
  "Face name to use for level-5 headers.")

(defvar markdown-header-face-6 'markdown-header-face-6
  "Face name to use for level-6 headers.")

(defvar markdown-inline-code-face 'markdown-inline-code-face
  "Face name to use for inline code.")

(defvar markdown-list-face 'markdown-list-face
  "Face name to use for list markers.")

(defvar markdown-blockquote-face 'markdown-blockquote-face
  "Face name to use for blockquote.")

(defvar markdown-pre-face 'markdown-pre-face
  "Face name to use for preformatted text.")

(defvar markdown-language-keyword-face 'markdown-language-keyword-face
  "Face name to use for programming language identifiers.")

(defvar markdown-link-face 'markdown-link-face
  "Face name to use for links.")

(defvar markdown-missing-link-face 'markdown-missing-link-face
  "Face name to use for links where the linked file does not exist.")

(defvar markdown-reference-face 'markdown-reference-face
  "Face name to use for reference.")

(defvar markdown-footnote-face 'markdown-footnote-face
  "Face name to use for footnote identifiers.")

(defvar markdown-url-face 'markdown-url-face
  "Face name to use for URLs.")

(defvar markdown-link-title-face 'markdown-link-title-face
  "Face name to use for reference link titles.")

(defvar markdown-line-break-face 'markdown-line-break-face
  "Face name to use for hard line breaks.")

(defvar markdown-comment-face 'markdown-comment-face
  "Face name to use for HTML comments.")

(defvar markdown-math-face 'markdown-math-face
  "Face name to use for LaTeX expressions.")

(defvar markdown-metadata-key-face 'markdown-metadata-key-face
  "Face name to use for metadata keys.")

(defvar markdown-metadata-value-face 'markdown-metadata-value-face
  "Face name to use for metadata values.")

(defvar markdown-gfm-checkbox-face 'markdown-gfm-checkbox-face
  "Face name to use for GFM checkboxes.")

(defvar markdown-highlight-face 'markdown-highlight-face
  "Face name to use for mouse highlighting.")

(defvar markdown-markup-face 'markdown-markup-face
  "Face name to use for markup elements.")

(defgroup markdown-faces nil
  "Faces used in Markdown Mode"
  :group 'markdown
  :group 'faces)

(defface markdown-italic-face
  '((t (:inherit font-lock-variable-name-face :slant italic :weight normal)))
  "Face for italic text."
  :group 'markdown-faces)

(defface markdown-bold-face
  '((t (:inherit font-lock-variable-name-face :weight bold :slant normal)))
  "Face for bold text."
  :group 'markdown-faces)

(defface markdown-strike-through-face
  '((t (:inherit font-lock-variable-name-face :strike-through t)))
  "Face for strike-through text."
  :group 'markdown-faces)

(defface markdown-markup-face
  '((t (:inherit shadow :slant normal :weight normal)))
  "Face for markup elements."
  :group 'markdown-faces)

(defface markdown-header-rule-face
  '((t (:inherit markdown-markup-face)))
  "Base face for headers rules."
  :group 'markdown-faces)

(defface markdown-header-delimiter-face
  '((t (:inherit markdown-markup-face)))
  "Base face for headers hash delimiter."
  :group 'markdown-faces)

(defface markdown-inline-code-face
  '((t (:inherit font-lock-constant-face)))
  "Face for inline code."
  :group 'markdown-faces)

(defface markdown-list-face
  '((t (:inherit markdown-markup-face)))
  "Face for list item markers."
  :group 'markdown-faces)

(defface markdown-blockquote-face
  '((t (:inherit font-lock-doc-face)))
  "Face for blockquote sections."
  :group 'markdown-faces)

(defface markdown-pre-face
  '((t (:inherit font-lock-constant-face)))
  "Face for preformatted text."
  :group 'markdown-faces)

(defface markdown-language-keyword-face
  '((t (:inherit font-lock-type-face)))
  "Face for programming language identifiers."
  :group 'markdown-faces)

(defface markdown-link-face
  '((t (:inherit font-lock-keyword-face)))
  "Face for links."
  :group 'markdown-faces)

(defface markdown-missing-link-face
  '((t (:inherit font-lock-warning-face)))
  "Face for missing links."
  :group 'markdown-faces)

(defface markdown-reference-face
  '((t (:inherit markdown-markup-face)))
  "Face for link references."
  :group 'markdown-faces)

(defface markdown-footnote-face
  '((t (:inherit markdown-markup-face)))
  "Face for footnote markers."
  :group 'markdown-faces)

(defface markdown-url-face
  '((t (:inherit font-lock-string-face)))
  "Face for URLs."
  :group 'markdown-faces)

(defface markdown-link-title-face
  '((t (:inherit font-lock-comment-face)))
  "Face for reference link titles."
  :group 'markdown-faces)

(defface markdown-line-break-face
  '((t (:inherit font-lock-constant-face :underline t)))
  "Face for hard line breaks."
  :group 'markdown-faces)

(defface markdown-comment-face
  '((t (:inherit font-lock-comment-face)))
  "Face for HTML comments."
  :group 'markdown-faces)

(defface markdown-math-face
  '((t (:inherit font-lock-string-face)))
  "Face for LaTeX expressions."
  :group 'markdown-faces)

(defface markdown-metadata-key-face
  '((t (:inherit font-lock-variable-name-face)))
  "Face for metadata keys."
  :group 'markdown-faces)

(defface markdown-metadata-value-face
  '((t (:inherit font-lock-string-face)))
  "Face for metadata values."
  :group 'markdown-faces)

(defface markdown-gfm-checkbox-face
  '((t (:inherit font-lock-builtin-face)))
  "Face for GFM checkboxes."
  :group 'markdown-faces)

(defface markdown-highlight-face
  '((t (:inherit highlight)))
  "Face for mouse highlighting."
  :group 'markdown-faces)

(defcustom markdown-header-scaling nil
  "Whether to use variable-height faces for headers.
When non-nil, `markdown-header-face' will inherit from
`variable-pitch' and the scaling values in
`markdown-header-scaling-values' will be applied to
headers of levels one through six respectively."
  :type 'boolean
  :initialize 'custom-initialize-default
  :set (lambda (symbol value)
         (set-default symbol value)
         (markdown-update-header-faces value))
  :group 'markdown-faces)

(defcustom markdown-header-scaling-values
  '(1.8 1.4 1.2 1.0 1.0 1.0)
  "List of scaling values for headers of level one through six.
Used when `markdown-header-scaling' is non-nil."
  :type 'list
  :initialize 'custom-initialize-default
  :set (lambda (symbol value)
         (set-default symbol value)
         (markdown-update-header-faces markdown-header-scaling value))
  :group 'markdown-faces)

(defun markdown-make-header-faces ()
  "Build the faces used for Markdown headers."
  (defface markdown-header-face
    `((t (:inherit (,@(when markdown-header-scaling 'variable-pitch)
                    font-lock-function-name-face)
                   :weight bold)))
    "Base face for headers."
    :group 'markdown-faces)
  (dotimes (num 6)
    (let* ((num1 (1+ num))
           (face-name (intern (format "markdown-header-face-%s" num1)))
           (scale (if markdown-header-scaling
                      (float (nth num markdown-header-scaling-values))
                    1.0)))
      (eval
       `(defface ,face-name
          '((t (:inherit markdown-header-face :height ,scale)))
          (format "Face for level %s headers.

You probably don't want to customize this face directly. Instead
you can customize the base face `markdown-header-face' or the
variable-height variable `markdown-header-scaling'." ,num1)
          :group 'markdown-faces)))))

(markdown-make-header-faces)

(defun markdown-update-header-faces (&optional scaling scaling-values)
  "Update header faces, depending on if header SCALING is desired.
If so, use given list of SCALING-VALUES relative to the baseline
size of `markdown-header-face'."
  (dotimes (num 6)
    (let* ((face-name (intern (format "markdown-header-face-%s" (1+ num))))
           (scale (cond ((not scaling) 1.0)
                        (scaling-values (float (nth num scaling-values)))
                        (t (float (nth num markdown-header-scaling-values))))))
      (unless (get face-name 'saved-face) ; Don't update customized faces
        (set-face-attribute face-name nil :height scale)))))

(defun markdown-syntactic-face (state)
  "Return font-lock face for characters with given STATE.
See `font-lock-syntactic-face-function' for details."
  (let ((in-comment (nth 4 state)))
    (cond
     (in-comment 'markdown-comment-face)
     (t nil))))

(defvar markdown-mode-font-lock-keywords-basic
  `((markdown-match-yaml-metadata-begin . ((1 markdown-markup-face)))
    (markdown-match-yaml-metadata-end . ((1 markdown-markup-face)))
    (markdown-match-yaml-metadata-key . ((1 markdown-metadata-key-face)
                                         (2 markdown-markup-face)
                                         (3 markdown-metadata-value-face)))
    (markdown-match-gfm-open-code-blocks . ((1 markdown-markup-face)
                                            (2 markdown-language-keyword-face nil t)))
    (markdown-match-gfm-close-code-blocks . ((1 markdown-markup-face)))
    (markdown-match-gfm-code-blocks . ((0 markdown-pre-face)))
    (markdown-match-fenced-start-code-block . ((1 markdown-markup-face)
                                               (2 markdown-language-keyword-face nil t)))
    (markdown-match-fenced-end-code-block . ((0 markdown-markup-face)))
    (markdown-match-fenced-code-blocks . ((0 markdown-pre-face)))
    (markdown-match-pre-blocks . ((0 markdown-pre-face)))
    (markdown-match-blockquotes . ((1 markdown-markup-face)
                                   (2 markdown-blockquote-face)))
    (markdown-match-heading-1-setext . ((1 markdown-header-face-1)
                                        (2 markdown-header-rule-face)))
    (markdown-match-heading-2-setext . ((1 markdown-header-face-2)
                                        (3 markdown-header-rule-face)))
    (markdown-match-heading-6-atx . ((4 markdown-header-delimiter-face)
                                     (5 markdown-header-face-6)
                                     (6 markdown-header-delimiter-face)))
    (markdown-match-heading-5-atx . ((4 markdown-header-delimiter-face)
                                     (5 markdown-header-face-5)
                                     (6 markdown-header-delimiter-face)))
    (markdown-match-heading-4-atx . ((4 markdown-header-delimiter-face)
                                     (5 markdown-header-face-4)
                                     (6 markdown-header-delimiter-face)))
    (markdown-match-heading-3-atx . ((4 markdown-header-delimiter-face)
                                     (5 markdown-header-face-3)
                                     (6 markdown-header-delimiter-face)))
    (markdown-match-heading-2-atx . ((4 markdown-header-delimiter-face)
                                     (5 markdown-header-face-2)
                                     (6 markdown-header-delimiter-face)))
    (markdown-match-heading-1-atx . ((4 markdown-header-delimiter-face)
                                     (5 markdown-header-face-1)
                                     (6 markdown-header-delimiter-face)))
    (markdown-match-declarative-metadata . ((1 markdown-metadata-key-face)
                                              (2 markdown-markup-face)
                                              (3 markdown-metadata-value-face)))
    (markdown-match-pandoc-metadata . ((1 markdown-markup-face)
                                       (2 markdown-markup-face)
                                       (3 markdown-metadata-value-face)))
    (markdown-match-hr . markdown-header-delimiter-face)
    (markdown-match-code . ((1 markdown-markup-face)
                            (2 markdown-inline-code-face)
                            (3 markdown-markup-face)))
    (,markdown-regex-kbd . ((1 markdown-markup-face)
                            (2 markdown-inline-code-face)
                            (3 markdown-markup-face)))
    (,markdown-regex-angle-uri . ((1 markdown-markup-face)
                                  (2 markdown-link-face)
                                  (3 markdown-markup-face)))
    (,markdown-regex-list . (2 markdown-list-face))
    (,markdown-regex-footnote . ((1 markdown-markup-face)          ; [^
                                 (2 markdown-footnote-face)        ; label
                                 (3 markdown-markup-face)))        ; ]
    (,markdown-regex-link-inline . ((1 markdown-markup-face nil t) ; ! (optional)
                                    (2 markdown-markup-face)       ; [
                                    (3 markdown-link-face)         ; text
                                    (4 markdown-markup-face)       ; ]
                                    (5 markdown-markup-face)       ; (
                                    (6 markdown-url-face)          ; url
                                    (7 markdown-link-title-face nil t) ; "title" (optional)
                                    (8 markdown-markup-face)))         ; )
    (,markdown-regex-link-reference . ((1 markdown-markup-face nil t) ; ! (optional)
                                       (2 markdown-markup-face)       ; [
                                       (3 markdown-link-face)         ; text
                                       (4 markdown-markup-face)       ; ]
                                       (5 markdown-markup-face)       ; [
                                       (6 markdown-reference-face)    ; label
                                       (7 markdown-markup-face)))     ; ]
    (,markdown-regex-reference-definition . ((1 markdown-markup-face) ; [
                                             (2 markdown-reference-face) ; label
                                             (3 markdown-markup-face)    ; ]
                                             (4 markdown-markup-face)    ; :
                                             (5 markdown-url-face)       ; url
                                             (6 markdown-link-title-face))) ; "title" (optional)
    ;; Math mode $..$
    (markdown-match-math-single . ((1 markdown-markup-face prepend)
                                   (2 markdown-math-face append)
                                   (3 markdown-markup-face prepend)))
    ;; Math mode $$..$$
    (markdown-match-math-double . ((1 markdown-markup-face prepend)
                                   (2 markdown-math-face append)
                                   (3 markdown-markup-face prepend)))
    (markdown-match-bold . ((1 markdown-markup-face prepend)
                            (2 markdown-bold-face append)
                            (3 markdown-markup-face prepend)))
    (markdown-match-italic . ((1 markdown-markup-face prepend)
                              (2 markdown-italic-face append)
                              (3 markdown-markup-face prepend)))
    (,markdown-regex-uri . markdown-link-face)
    (,markdown-regex-email . markdown-link-face)
    (,markdown-regex-line-break . (1 markdown-line-break-face prepend)))

  "Syntax highlighting for Markdown files.")

(defvar markdown-mode-font-lock-keywords nil
  "Default highlighting expressions for Markdown mode.
This variable is defined as a buffer-local variable for dynamic
extension support.")

;; Footnotes
(defvar markdown-footnote-counter 0
  "Counter for footnote numbers.")
(make-variable-buffer-local 'markdown-footnote-counter)

(defconst markdown-footnote-chars
  "[[:alnum:]-]"
  "Regular expression matching any character that is allowed in a footnote identifier.")

(defconst markdown-regex-footnote-definition
  (concat "^\\[\\(\\^" markdown-footnote-chars "*?\\)\\]:\\(?:[ \t]+\\|$\\)")
  "Regular expression matching a footnote definition, capturing the label.")

\f
;;; Compatibility =============================================================

(defun markdown-replace-regexp-in-string (regexp rep string)
  "Replace ocurrences of REGEXP with REP in STRING.
This is a compatibility wrapper to provide `replace-regexp-in-string'
in XEmacs 21."
  (if (featurep 'xemacs)
      (replace-in-string string regexp rep)
    (replace-regexp-in-string regexp rep string)))

;; `markdown-use-region-p' is a compatibility function which checks
;; for an active region, with fallbacks for older Emacsen and XEmacs.
(eval-and-compile
  (cond
   ;; Emacs 24 and newer
   ((fboundp 'use-region-p)
    (defalias 'markdown-use-region-p 'use-region-p))
   ;; XEmacs
   ((fboundp 'region-active-p)
    (defalias 'markdown-use-region-p 'region-active-p))))

(defun markdown-use-buttons-p ()
  "Determine whether this Emacs supports buttons."
  (or (featurep 'button) (locate-library "button")))

;; Use new names for outline-mode functions in Emacs 25 and later.
(eval-and-compile
  (defalias 'markdown-hide-sublevels
    (if (fboundp 'outline-hide-sublevels)
        'outline-hide-sublevels
      'hide-sublevels))
  (defalias 'markdown-show-all
    (if (fboundp 'outline-show-all)
        'outline-show-all
      'show-all))
  (defalias 'markdown-hide-body
    (if (fboundp 'outline-hide-body)
        'outline-hide-body
      'hide-body))
  (defalias 'markdown-show-children
    (if (fboundp 'outline-show-children)
        'outline-show-children
      'show-children))
  (defalias 'markdown-show-subtree
    (if (fboundp 'outline-show-subtree)
        'outline-show-subtree
      'show-subtree))
  (defalias 'markdown-hide-subtree
    (if (fboundp 'outline-hide-subtree)
        'outline-hide-subtree
      'hide-subtree)))

;; Provide directory-name-p to Emacs 24
(defsubst markdown-directory-name-p (name)
  "Return non-nil if NAME ends with a directory separator character.
Taken from `directory-name-p' from Emacs 25 and provided here for
backwards compatibility."
  (let ((len (length name))
        (lastc ?.))
    (if (> len 0)
        (setq lastc (aref name (1- len))))
    (or (= lastc ?/)
        (and (memq system-type '(windows-nt ms-dos))
             (= lastc ?\\)))))

;; Provide a function to find files recursively Emacs 24
(if (fboundp 'directory-files-recursively)
    (defalias 'markdown-directory-files-recursively 'directory-files-recursively)
  (defun markdown-directory-files-recursively (dir regexp)
    "Return list of all files under DIR that have file names matching REGEXP.
This function works recursively.  Files are returned in \"depth first\"
order, and files from each directory are sorted in alphabetical order.
Each file name appears in the returned list in its absolute form.
Based on `directory-files-recursively' from Emacs 25 and provided
here for backwards compatibility."
    (let ((result nil)
          (files nil)
          ;; When DIR is "/", remote file names like "/method:" could
          ;; also be offered.  We shall suppress them.
          (tramp-mode (and tramp-mode (file-remote-p (expand-file-name dir)))))
      (dolist (file (sort (file-name-all-completions "" dir)
                          'string<))
        (unless (member file '("./" "../"))
          (if (markdown-directory-name-p file)
              (let* ((leaf (substring file 0 (1- (length file))))
                     (full-file (expand-file-name leaf dir)))
                (setq result
                      (nconc result (markdown-directory-files-recursively
                                     full-file regexp))))
            (when (string-match regexp file)
              (push (expand-file-name file dir) files)))))
      (nconc result (nreverse files)))))

\f
;;; Markdown Parsing Functions ================================================

(defun markdown-cur-line-blank-p ()
  "Return t if the current line is blank and nil otherwise."
  (save-excursion
    (beginning-of-line)
    (looking-at-p "^\\s *$")))

(defun markdown-prev-line-blank-p ()
  "Return t if the previous line is blank and nil otherwise.
If we are at the first line, then consider the previous line to be blank."
  (or (= (line-beginning-position) (point-min))
      (save-excursion
        (forward-line -1)
        (markdown-cur-line-blank-p))))

(defun markdown-next-line-blank-p ()
  "Return t if the next line is blank and nil otherwise.
If we are at the last line, then consider the next line to be blank."
  (or (= (line-end-position) (point-max))
      (save-excursion
        (forward-line 1)
        (markdown-cur-line-blank-p))))

(defun markdown-prev-line-indent ()
  "Return the number of leading whitespace characters in the previous line.
Return 0 if the current line is the first line in the buffer."
  (save-excursion
    (if (= (line-beginning-position) (point-min))
        0
      (forward-line -1)
      (current-indentation))))

(defun markdown-next-line-indent ()
  "Return the number of leading whitespace characters in the next line.
Return 0 if line is the last line in the buffer."
  (save-excursion
    (if (= (line-end-position) (point-max))
        0
      (forward-line 1)
      (current-indentation))))

(defun markdown-cur-non-list-indent ()
  "Return beginning position of list item text (not including the list marker).
Return nil if the current line is not the beginning of a list item."
  (save-match-data
    (save-excursion
      (beginning-of-line)
      (when (re-search-forward markdown-regex-list (line-end-position) t)
        (current-column)))))

(defun markdown-prev-non-list-indent ()
  "Return position of the first non-list-marker on the previous line."
  (save-excursion
    (forward-line -1)
    (markdown-cur-non-list-indent)))

(defun markdown-new-baseline-p ()
  "Determine if the current line begins a new baseline level."
  (save-excursion
    (beginning-of-line)
    (or (looking-at-p markdown-regex-header)
        (looking-at-p markdown-regex-hr)
        (and (null (markdown-cur-non-list-indent))
             (= (current-indentation) 0)
             (markdown-prev-line-blank-p)))))

(defun markdown-search-backward-baseline ()
  "Search backward baseline point with no indentation and not a list item."
  (end-of-line)
  (let (stop)
    (while (not (or stop (bobp)))
      (re-search-backward markdown-regex-block-separator nil t)
      (when (match-end 2)
        (goto-char (match-end 2))
        (cond
         ((markdown-new-baseline-p)
          (setq stop t))
         ((looking-at-p markdown-regex-list)
          (setq stop nil))
         (t (setq stop t)))))))

(defun markdown-update-list-levels (marker indent levels)
  "Update list levels given list MARKER, block INDENT, and current LEVELS.
Here, MARKER is a string representing the type of list, INDENT is an integer
giving the indentation, in spaces, of the current block, and LEVELS is a
list of the indentation levels of parent list items.  When LEVELS is nil,
it means we are at baseline (not inside of a nested list)."
  (cond
   ;; New list item at baseline.
   ((and marker (null levels))
    (setq levels (list indent)))
   ;; List item with greater indentation (four or more spaces).
   ;; Increase list level.
   ((and marker (>= indent (+ (car levels) 4)))
    (setq levels (cons indent levels)))
   ;; List item with greater or equal indentation (less than four spaces).
   ;; Do not increase list level.
   ((and marker (>= indent (car levels)))
    levels)
   ;; Lesser indentation level.
   ;; Pop appropriate number of elements off LEVELS list (e.g., lesser
   ;; indentation could move back more than one list level).  Note
   ;; that this block need not be the beginning of list item.
   ((< indent (car levels))
    (while (and (> (length levels) 1)
                (< indent (+ (cadr levels) 4)))
      (setq levels (cdr levels)))
    levels)
   ;; Otherwise, do nothing.
   (t levels)))

(defun markdown-calculate-list-levels ()
  "Calculate list levels at point.
Return a list of the form (n1 n2 n3 ...) where n1 is the
indentation of the deepest nested list item in the branch of
the list at the point, n2 is the indentation of the parent
list item, and so on.  The depth of the list item is therefore
the length of the returned list.  If the point is not at or
immediately  after a list item, return nil."
  (save-excursion
    (let ((first (point)) levels indent pre-regexp)
      ;; Find a baseline point with zero list indentation
      (markdown-search-backward-baseline)
      ;; Search for all list items between baseline and LOC
      (while (and (< (point) first)
                  (re-search-forward markdown-regex-list first t))
        (setq pre-regexp (format "^\\(    \\|\t\\)\\{%d\\}" (1+ (length levels))))
        (beginning-of-line)
        (cond
         ;; Make sure this is not a header or hr
         ((markdown-new-baseline-p) (setq levels nil))
         ;; Make sure this is not a line from a pre block
         ((looking-at-p pre-regexp))
         ;; If not, then update levels
         (t
          (setq indent (current-indentation))
          (setq levels (markdown-update-list-levels (match-string 2)
                                                    indent levels))))
        (end-of-line))
      levels)))

(defun markdown-prev-list-item (level)
  "Search backward from point for a list item with indentation LEVEL.
Set point to the beginning of the item, and return point, or nil
upon failure."
  (let (bounds indent prev)
    (setq prev (point))
    (forward-line -1)
    (setq indent (current-indentation))
    (while
        (cond
         ;; List item
         ((and (looking-at-p markdown-regex-list)
               (setq bounds (markdown-cur-list-item-bounds)))
          (cond
           ;; Stop and return point at item of lesser or equal indentation
           ((<= (nth 3 bounds) level)
            (setq prev (point))
            nil)
           ;; Stop at beginning of buffer
           ((bobp) (setq prev nil))
           ;; Continue at item with greater indentation
           ((> (nth 3 bounds) level) t)))
         ;; Stop at beginning of buffer
         ((bobp) (setq prev nil))
         ;; Continue if current line is blank
         ((markdown-cur-line-blank-p) t)
         ;; Continue while indentation is the same or greater
         ((>= indent level) t)
         ;; Stop if current indentation is less than list item
         ;; and the next is blank
         ((and (< indent level)
               (markdown-next-line-blank-p))
          (setq prev nil))
         ;; Stop at a header
         ((looking-at-p markdown-regex-header) (setq prev nil))
         ;; Stop at a horizontal rule
         ((looking-at-p markdown-regex-hr) (setq prev nil))
         ;; Otherwise, continue.
         (t t))
      (forward-line -1)
      (setq indent (current-indentation)))
    prev))

(defun markdown-next-list-item (level)
  "Search forward from point for the next list item with indentation LEVEL.
Set point to the beginning of the item, and return point, or nil
upon failure."
  (let (bounds indent next)
    (setq next (point))
    (forward-line)
    (setq indent (current-indentation))
    (while
        (cond
         ;; Stop at end of the buffer.
         ((eobp) nil)
         ;; Continue if the current line is blank
         ((markdown-cur-line-blank-p) t)
         ;; List item
         ((and (looking-at-p markdown-regex-list)
               (setq bounds (markdown-cur-list-item-bounds)))
          (cond
           ;; Continue at item with greater indentation
           ((> (nth 3 bounds) level) t)
           ;; Stop and return point at item of equal indentation
           ((= (nth 3 bounds) level)
            (setq next (point))
            nil)
           ;; Stop and return nil at item with lesser indentation
           ((< (nth 3 bounds) level)
            (setq next nil)
            nil)))
         ;; Continue while indentation is the same or greater
         ((>= indent level) t)
         ;; Stop if current indentation is less than list item
         ;; and the previous line was blank.
         ((and (< indent level)
               (markdown-prev-line-blank-p))
          (setq next nil))
         ;; Stop at a header
         ((looking-at-p markdown-regex-header) (setq next nil))
         ;; Stop at a horizontal rule
         ((looking-at-p markdown-regex-hr) (setq next nil))
         ;; Otherwise, continue.
         (t t))
      (forward-line)
      (setq indent (current-indentation)))
    next))

(defun markdown-cur-list-item-end (level)
  "Move to the end of the current list item with nonlist indentation LEVEL.
If the point is not in a list item, do nothing."
  (let (indent)
    (forward-line)
    (setq indent (current-indentation))
    (while
        (cond
         ;; Stop at end of the buffer.
         ((eobp) nil)
         ;; Continue if the current line is blank
         ((markdown-cur-line-blank-p) t)
         ;; Continue while indentation is the same or greater
         ((>= indent level) t)
         ;; Stop if current indentation is less than list item
         ;; and the previous line was blank.
         ((and (< indent level)
               (markdown-prev-line-blank-p))
          nil)
         ;; Stop at a new list item of the same or lesser indentation
         ((looking-at-p markdown-regex-list) nil)
         ;; Stop at a header
         ((looking-at-p markdown-regex-header) nil)
         ;; Stop at a horizontal rule
         ((looking-at-p markdown-regex-hr) nil)
         ;; Otherwise, continue.
         (t t))
      (forward-line)
      (setq indent (current-indentation)))
    ;; Don't skip over whitespace for empty list items (marker and
    ;; whitespace only), just move to end of whitespace.
    (if (looking-back (concat markdown-regex-list "\\s-*") nil)
        (goto-char (match-end 3))
      (skip-syntax-backward "-"))))

(defun markdown-cur-list-item-bounds ()
  "Return bounds and indentation of the current list item.
Return a list of the form (begin end indent nonlist-indent marker).
If the point is not inside a list item, return nil.
Leave match data intact for `markdown-regex-list'."
  (let (cur prev-begin prev-end indent nonlist-indent marker)
    ;; Store current location
    (setq cur (point))
    ;; Verify that cur is between beginning and end of item
    (save-excursion
      (end-of-line)
      (when (re-search-backward markdown-regex-list nil t)
        (setq prev-begin (match-beginning 0))
        (setq indent (length (match-string 1)))
        (setq nonlist-indent (length (match-string 0)))
        (setq marker (concat (match-string 2) (match-string 3)))
        (save-match-data
          (markdown-cur-list-item-end nonlist-indent)
          (setq prev-end (point)))
        (when (and (>= cur prev-begin)
                   (<= cur prev-end)
                   nonlist-indent)
          (list prev-begin prev-end indent nonlist-indent marker))))))

(defun markdown-bounds-of-thing-at-point (thing)
  "Call `bounds-of-thing-at-point' for THING with slight modifications.
Does not include trailing newlines when THING is 'line.  Handles the
end of buffer case by setting both endpoints equal to the value of
`point-max', since an empty region will trigger empty markup insertion.
Return bounds of form (beg . end) if THING is found, or nil otherwise."
  (let* ((bounds (bounds-of-thing-at-point thing))
         (a (car bounds))
         (b (cdr bounds)))
    (when bounds
      (when (eq thing 'line)
        (cond ((and (eobp) (markdown-cur-line-blank-p))
               (setq a b))
              ((char-equal (char-before b) ?\^J)
               (setq b (1- b)))))
      (cons a b))))

(defun markdown-reference-definition (reference)
  "Find out whether Markdown REFERENCE is defined.
REFERENCE should not include the square brackets.
When REFERENCE is defined, return a list of the form (text start end)
containing the definition text itself followed by the start and end
locations of the text.  Otherwise, return nil.
Leave match data for `markdown-regex-reference-definition'
intact additional processing."
  (let ((reference (downcase reference)))
    (save-excursion
      (goto-char (point-min))
      (catch 'found
        (while (re-search-forward markdown-regex-reference-definition nil t)
          (when (string= reference (downcase (match-string-no-properties 2)))
            (throw 'found
                   (list (match-string-no-properties 5)
                         (match-beginning 5) (match-end 5)))))))))

(defun markdown-get-defined-references ()
  "Return a list of all defined reference labels (not including square brackets)."
  (save-excursion
    (goto-char (point-min))
    (let (refs)
      (while (re-search-forward markdown-regex-reference-definition nil t)
        (let ((target (match-string-no-properties 2)))
          (cl-pushnew target refs :test #'equal)))
      (reverse refs))))

(defun markdown-inline-code-at-point ()
  "Return non-nil if the point is at an inline code fragment.
Return nil otherwise.  Set match data according to
`markdown-match-code' upon success.
This function searches the block for a code fragment that
contains the point using `markdown-match-code'.  We do this
because `thing-at-point-looking-at' does not work reliably with
`markdown-regex-code'.

The match data is set as follows:
Group 1 matches the opening backticks.
Group 2 matches the code fragment itself, without backticks.
Group 3 matches the closing backticks."
  (save-excursion
    (let ((old-point (point))
          (end-of-block (progn (markdown-end-of-block) (point)))
          found)
      (markdown-beginning-of-block)
      (while (and (markdown-match-code end-of-block)
                  (setq found t)
                  (< (match-end 0) old-point)))
      (and found                              ; matched something
           (<= (match-beginning 0) old-point) ; match contains old-point
           (>= (match-end 0) old-point)))))

(defun markdown-inline-code-at-point-p ()
  "Return non-nil if there is inline code at the point.
This is a predicate function counterpart to
`markdown-inline-code-at-point' which does not modify the match
data.  See `markdown-code-block-at-point-p' for code blocks."
  (save-match-data (markdown-inline-code-at-point)))

(make-obsolete 'markdown-code-at-point-p 'markdown-inline-code-at-point-p "2017-05-10")

(defun markdown-code-block-at-pos (pos)
  "Return match data list if there is a code block at POS.
This includes pre blocks, tilde-fenced code blocks, and GFM
quoted code blocks.  Return nil otherwise."
  (or (get-text-property pos 'markdown-pre)
      (markdown-get-enclosing-fenced-block-construct pos)
      ;; polymode removes text properties set by markdown-mode, so
      ;; check if `poly-markdown-mode' is active and whether the
      ;; `chunkmode' property is non-nil at POS.
      (and (bound-and-true-p poly-markdown-mode)
           (get-text-property pos 'chunkmode))))

(defun markdown-code-block-at-point ()
  "Return match data if the point is inside a code block.
This includes pre blocks, tilde-fenced code blocks, and
GFM quoted code blocks.  Calls `markdown-code-block-at-pos'."
  (markdown-code-block-at-pos (point)))

(defun markdown-code-block-at-point-p ()
  "Return non-nil if there is a code block at the point.
This includes pre blocks, tilde-fenced code blocks, and GFM
quoted code blocks.  This is a predicate function counterpart to
`markdown-code-block-at-point' which does not modify the match
data. See `markdown-inline-code-at-point-p' for inline code."
  (save-match-data (markdown-code-block-at-point)))

\f
;;; Markdown Font Lock Matching Functions =====================================

(defun markdown-range-property-any (begin end prop prop-values)
  "Return t if PROP from BEGIN to END is equal to one of the given PROP-VALUES.
Also returns t if PROP is a list containing one of the PROP-VALUES.
Return nil otherwise."
  (let (props)
    (catch 'found
      (dolist (loc (number-sequence begin end))
        (when (setq props (get-char-property loc prop))
          (cond ((listp props)
                 ;; props is a list, check for membership
                 (dolist (val prop-values)
                   (when (memq val props) (throw 'found loc))))
                (t
                 ;; props is a scalar, check for equality
                 (dolist (val prop-values)
                   (when (eq val props) (throw 'found loc))))))))))

(defun markdown-range-properties-exist (begin end props)
  (cl-loop
   for loc in (number-sequence begin end)
   with result = nil
   while (not
          (setq result
                (cl-some (lambda (prop) (get-char-property loc prop)) props)))
   finally return result))

(defun markdown-match-inline-generic (regex last)
  "Match inline REGEX from the point to LAST."
  (when (re-search-forward regex last t)
    (let ((bounds (markdown-code-block-at-pos (match-beginning 1))))
      (if (null bounds)
          ;; Not in a code block: keep match data and return t when in bounds
          (<= (match-end 0) last)
        ;; In code block: move past it and recursively search again
        (when (< (goto-char (nth 1 bounds)) last)
          (markdown-match-inline-generic regex last))))))

(defun markdown-match-code (last)
  "Match inline code fragments from point to LAST."
  (unless (bobp)
    (backward-char 1))
  (when (markdown-match-inline-generic markdown-regex-code last)
    (set-match-data (list (match-beginning 1) (match-end 1)
                          (match-beginning 2) (match-end 2)
                          (match-beginning 3) (match-end 3)
                          (match-beginning 4) (match-end 4)))
    (goto-char (1+ (match-end 0)))))

(defun markdown-match-bold (last)
  "Match inline bold from the point to LAST."
  (when (markdown-match-inline-generic markdown-regex-bold last)
    (let ((begin (match-beginning 2)) (end (match-end 2)))
      (cond
       ((markdown-range-property-any
         begin end 'face (list markdown-inline-code-face
                               markdown-math-face))
        (goto-char (1+ (match-end 0)))
        (markdown-match-bold last))
       (t
        (set-match-data (list (match-beginning 2) (match-end 2)
                          (match-beginning 3) (match-end 3)
                          (match-beginning 4) (match-end 4)
                          (match-beginning 5) (match-end 5)))
        (goto-char (1+ (match-end 0))))))))

(defun markdown-match-italic (last)
  "Match inline italics from the point to LAST."
  (let ((regex (if (eq major-mode 'gfm-mode)
                   markdown-regex-gfm-italic markdown-regex-italic)))
    (when (markdown-match-inline-generic regex last)
      (let ((begin (match-beginning 1)) (end (match-end 1)))
        (cond
         ((markdown-range-property-any
           begin begin 'face (list markdown-url-face))
          ;; Italics shouldn't begin inside a URL due to an underscore
          (goto-char (min (1+ (match-end 0)) last))
          (markdown-match-italic last))
         ((markdown-range-property-any
           begin end 'face (list markdown-inline-code-face
                                 markdown-bold-face
                                 markdown-list-face
                                 markdown-math-face))
          (goto-char (1+ (match-end 0)))
          (markdown-match-italic last))
         (t
          (set-match-data (list (match-beginning 1) (match-end 1)
                                (match-beginning 2) (match-end 2)
                                (match-beginning 3) (match-end 3)
                                (match-beginning 4) (match-end 4)))
          (goto-char (1+ (match-end 0)))))))))

(defun markdown-match-math-generic (regex last)
  "Match REGEX from point to LAST.
REGEX is either `markdown-regex-math-inline-single' for matching
$..$ or `markdown-regex-math-inline-double' for matching $$..$$."
  (when (and markdown-enable-math (markdown-match-inline-generic regex last))
    (let ((begin (match-beginning 1)) (end (match-end 1)))
      (prog1
          (if (or (markdown-range-property-any
                   begin end 'face (list markdown-inline-code-face
                                         markdown-bold-face))
                  (markdown-range-properties-exist
                   begin end
                   (markdown-get-fenced-block-middle-properties)))
              (markdown-match-math-generic regex last)
            t)
        (goto-char (1+ (match-end 0)))))))

(defun markdown-match-math-single (last)
  "Match single quoted $..$ math from point to LAST."
  (markdown-match-math-generic markdown-regex-math-inline-single last))

(defun markdown-match-math-double (last)
  "Match double quoted $$..$$ math from point to LAST."
  (markdown-match-math-generic markdown-regex-math-inline-double last))

(defun markdown-match-propertized-text (property last)
  "Match text with PROPERTY from point to LAST.
Restore match data previously stored in PROPERTY."
  (let ((saved (get-text-property (point) property))
        pos)
    (unless saved
      (setq pos (next-single-char-property-change (point) property nil last))
      (setq saved (get-text-property pos property)))
    (when saved
      (set-match-data saved)
      ;; Step at least one character beyond point. Otherwise
      ;; `font-lock-fontify-keywords-region' infloops.
      (goto-char (min (1+ (max (match-end 0) (point)))
                      (point-max)))
      saved)))

(defun markdown-match-pre-blocks (last)
  "Match preformatted blocks from point to LAST.
Use data stored in 'markdown-pre text property during syntax
analysis."
  (markdown-match-propertized-text 'markdown-pre last))

(defun markdown-match-gfm-code-blocks (last)
  "Match GFM quoted code blocks from point to LAST.
Use data stored in 'markdown-gfm-code text property during syntax
analysis."
  (markdown-match-propertized-text 'markdown-gfm-code last))

(defun markdown-match-gfm-open-code-blocks (last)
  (markdown-match-propertized-text 'markdown-gfm-block-begin last))

(defun markdown-match-gfm-close-code-blocks (last)
  (markdown-match-propertized-text 'markdown-gfm-block-end last))

(defun markdown-match-fenced-code-blocks (last)
  "Match fenced code blocks from the point to LAST."
  (markdown-match-propertized-text 'markdown-fenced-code last))

(defun markdown-match-fenced-start-code-block (last)
  (markdown-match-propertized-text 'markdown-tilde-fence-begin last))

(defun markdown-match-fenced-end-code-block (last)
  (markdown-match-propertized-text 'markdown-tilde-fence-end last))

(defun markdown-match-blockquotes (last)
  "Match blockquotes from point to LAST.
Use data stored in 'markdown-blockquote text property during syntax
analysis."
  (markdown-match-propertized-text 'markdown-blockquote last))

(defun markdown-match-heading-1-setext (last)
  "Match level 1 setext headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-1-setext last))

(defun markdown-match-heading-2-setext (last)
  "Match level 2 setext headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-2-setext last))

(defun markdown-match-heading-1-atx (last)
  "Match level 1 ATX headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-1-atx last))

(defun markdown-match-heading-2-atx (last)
  "Match level 2 ATX headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-2-atx last))

(defun markdown-match-heading-3-atx (last)
  "Match level 3 ATX headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-3-atx last))

(defun markdown-match-heading-4-atx (last)
  "Match level 4 ATX headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-4-atx last))

(defun markdown-match-heading-5-atx (last)
  "Match level 5 ATX headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-5-atx last))

(defun markdown-match-heading-6-atx (last)
  "Match level 6 ATX headings from point to LAST."
  (markdown-match-propertized-text 'markdown-heading-6-atx last))

(defun markdown-match-hr (last)
  "Match horizontal rules comments from the point to LAST."
  (while (and (re-search-forward markdown-regex-hr last t)
              (or (markdown-on-heading-p)
                  (markdown-code-block-at-point))
              (< (match-end 0) last))
    (forward-line))
  (beginning-of-line)
  (cond ((looking-at-p markdown-regex-hr)
         (forward-line)
         t)
        (t nil)))

(defun markdown-match-comments (last)
  "Match HTML comments from the point to LAST."
  (when (and (skip-syntax-forward "^<" last))
    (let ((beg (point)))
      (when (and (skip-syntax-forward "^>" last) (< (point) last))
        (forward-char)
        (set-match-data (list beg (point)))
        t))))

(defun markdown-get-match-boundaries (start-header end-header last &optional pos)
  (save-excursion
    (goto-char (or pos (point-min)))
    (cl-loop
     with cur-result = nil
     and st-hdr = (or start-header "\\`")
     and end-hdr = (or end-header "\n\n\\|\n\\'\\|\\'")
     while (and (< (point) last)
                (re-search-forward st-hdr last t)
                (progn
                  (setq cur-result (match-data))
                  (re-search-forward end-hdr nil t)))
     collect (list cur-result (match-data)))))

(defvar markdown-conditional-search-function #'re-search-forward
  "Conditional search function used in `markdown-search-until-condition'.
Made into a variable to allow for dynamic let-binding.")

(defun markdown-search-until-condition (condition &rest args)
  (let (ret)
    (while (and (not ret) (apply markdown-conditional-search-function args))
      (setq ret (funcall condition)))
    ret))

(defun markdown-match-generic-metadata
    (regexp last &optional start-header end-header)
  "Match generic metadata specified by REGEXP from the point to LAST.
If START-HEADER is nil, we assume metadata can only occur at the
very top of a file (\"\\`\"). If END-HEADER is nil, we assume it
is \"\n\n\""
  (let* ((header-bounds
          (markdown-get-match-boundaries start-header end-header last))
         (enclosing-header
          (cl-find-if                   ; just take first if multiple
           (lambda (match-bounds)
             (cl-destructuring-bind (begin end) (cl-second match-bounds)
               (and (< (point) begin)
                    (save-excursion (re-search-forward regexp end t)))))
           header-bounds))
         (header-begin
          (when enclosing-header (cl-second (cl-first enclosing-header))))
         (header-end
          (when enclosing-header (cl-first (cl-second enclosing-header)))))
    (cond ((null enclosing-header)
           ;; Don't match anything outside of a header.
           nil)
          ((markdown-search-until-condition
            (lambda () (> (point) header-begin)) regexp (min last header-end) t)
           ;; If a metadata item is found, it may span several lines.
           (let ((key-beginning (match-beginning 1))
                 (key-end (match-end 1))
                 (markup-begin (match-beginning 2))
                 (markup-end (match-end 2))
                 (value-beginning (match-beginning 3)))
             (set-match-data (list key-beginning (point) ; complete metadata
                                   key-beginning key-end ; key
                                   markup-begin markup-end ; markup
                                   value-beginning (point))) ; value
             t))
          (t nil))))

(defun markdown-match-declarative-metadata (last)
  "Match declarative metadata from the point to LAST."
  (markdown-match-generic-metadata markdown-regex-declarative-metadata last))

(defun markdown-match-pandoc-metadata (last)
  "Match Pandoc metadata from the point to LAST."
  (markdown-match-generic-metadata markdown-regex-pandoc-metadata last))

(defun markdown-match-yaml-metadata-begin (last)
  (markdown-match-propertized-text 'markdown-yaml-metadata-begin last))

(defun markdown-match-yaml-metadata-end (last)
  (markdown-match-propertized-text 'markdown-yaml-metadata-end last))

(defun markdown-match-yaml-metadata-key (last)
  (markdown-match-propertized-text 'markdown-metadata-key last))

\f
;;; Syntax Table ==============================================================

(defvar markdown-mode-syntax-table
  (let ((tab (make-syntax-table text-mode-syntax-table)))
    (modify-syntax-entry ?\" "." tab)
    tab)
  "Syntax table for `markdown-mode'.")

\f
;;; Element Insertion =========================================================

(defun markdown-ensure-blank-line-before ()
  "If previous line is not already blank, insert a blank line before point."
  (unless (bolp) (insert "\n"))
  (unless (or (bobp) (looking-back "\n\\s-*\n" nil)) (insert "\n")))

(defun markdown-ensure-blank-line-after ()
  "If following line is not already blank, insert a blank line after point.
Return the point where it was originally."
  (save-excursion
    (unless (eolp) (insert "\n"))
    (unless (or (eobp) (looking-at-p "\n\\s-*\n")) (insert "\n"))))

(defun markdown-wrap-or-insert (s1 s2 &optional thing beg end)
  "Insert the strings S1 and S2, wrapping around region or THING.
If a region is specified by the optional BEG and END arguments,
wrap the strings S1 and S2 around that region.
If there is an active region, wrap the strings S1 and S2 around
the region.  If there is not an active region but the point is at
THING, wrap that thing (which defaults to word).  Otherwise, just
insert S1 and S2 and place the cursor in between.  Return the
bounds of the entire wrapped string, or nil if nothing was wrapped
and S1 and S2 were only inserted."
  (let (a b bounds new-point)
    (cond
     ;; Given region
     ((and beg end)
      (setq a beg
            b end
            new-point (+ (point) (length s1))))
     ;; Active region
     ((markdown-use-region-p)
      (setq a (region-beginning)
            b (region-end)
            new-point (+ (point) (length s1))))
     ;; Thing (word) at point
     ((setq bounds (markdown-bounds-of-thing-at-point (or thing 'word)))
      (setq a (car bounds)
            b (cdr bounds)
            new-point (+ (point) (length s1))))
     ;; No active region and no word
     (t
      (setq a (point)
            b (point))))
    (goto-char b)
    (insert s2)
    (goto-char a)
    (insert s1)
    (when new-point (goto-char new-point))
    (if (= a b)
        nil
      (setq b (+ b (length s1) (length s2)))
      (cons a b))))

(defun markdown-point-after-unwrap (cur prefix suffix)
  "Return desired position of point after an unwrapping operation.
CUR gives the position of the point before the operation.
Additionally, two cons cells must be provided.  PREFIX gives the
bounds of the prefix string and SUFFIX gives the bounds of the
suffix string."
  (cond ((< cur (cdr prefix)) (car prefix))
        ((< cur (car suffix)) (- cur (- (cdr prefix) (car prefix))))
        ((<= cur (cdr suffix))
         (- cur (+ (- (cdr prefix) (car prefix))
                   (- cur (car suffix)))))
        (t cur)))

(defun markdown-unwrap-thing-at-point (regexp all text)
  "Remove prefix and suffix of thing at point and reposition the point.
When the thing at point matches REGEXP, replace the subexpression
ALL with the string in subexpression TEXT.  Reposition the point
in an appropriate location accounting for the removal of prefix
and suffix strings.  Return new bounds of string from group TEXT.
When REGEXP is nil, assumes match data is already set."
  (when (or (null regexp)
            (thing-at-point-looking-at regexp))
    (let ((cur (point))
          (prefix (cons (match-beginning all) (match-beginning text)))
          (suffix (cons (match-end text) (match-end all)))
          (bounds (cons (match-beginning text) (match-end text))))
      ;; Replace the thing at point
      (replace-match (match-string text) t t nil all)
      ;; Reposition the point
      (goto-char (markdown-point-after-unwrap cur prefix suffix))
      ;; Adjust bounds
      (setq bounds (cons (car prefix)
                         (- (cdr bounds) (- (cdr prefix) (car prefix))))))))

(defun markdown-unwrap-things-in-region (beg end regexp all text)
  "Remove prefix and suffix of all things in region from BEG to END.
When a thing in the region matches REGEXP, replace the
subexpression ALL with the string in subexpression TEXT.
Return a cons cell containing updated bounds for the region."
  (save-excursion
    (goto-char beg)
    (let ((removed 0) len-all len-text)
      (while (re-search-forward regexp (- end removed) t)
        (setq len-all (length (match-string-no-properties all)))
        (setq len-text (length (match-string-no-properties text)))
        (setq removed (+ removed (- len-all len-text)))
        (replace-match (match-string text) t t nil all))
      (cons beg (- end removed)))))

(defun markdown-insert-hr (arg)
  "Insert or replace a horizonal rule.
By default, use the first element of `markdown-hr-strings'.  When
ARG is non-nil, as when given a prefix, select a different
element as follows.  When prefixed with \\[universal-argument],
use the last element of `markdown-hr-strings' instead.  When
prefixed with an integer from 1 to the length of
`markdown-hr-strings', use the element in that position instead."
  (interactive "*P")
  (when (thing-at-point-looking-at markdown-regex-hr)
    (delete-region (match-beginning 0) (match-end 0)))
  (markdown-ensure-blank-line-before)
  (cond ((equal arg '(4))
         (insert (car (reverse markdown-hr-strings))))
        ((and (integerp arg) (> arg 0)
              (<= arg (length markdown-hr-strings)))
         (insert (nth (1- arg) markdown-hr-strings)))
        (t
         (insert (car markdown-hr-strings))))
  (markdown-ensure-blank-line-after))

(defun markdown-insert-bold ()
  "Insert markup to make a region or word bold.
If there is an active region, make the region bold.  If the point
is at a non-bold word, make the word bold.  If the point is at a
bold word or phrase, remove the bold markup.  Otherwise, simply
insert bold delimiters and place the cursor in between them."
  (interactive)
  (let ((delim (if markdown-bold-underscore "__" "**")))
    (if (markdown-use-region-p)
        ;; Active region
        (let ((bounds (markdown-unwrap-things-in-region
                       (region-beginning) (region-end)
                       markdown-regex-bold 2 4)))
          (markdown-wrap-or-insert delim delim nil (car bounds) (cdr bounds)))
      ;; Bold markup removal, bold word at point, or empty markup insertion
      (if (thing-at-point-looking-at markdown-regex-bold)
          (markdown-unwrap-thing-at-point nil 2 4)
        (markdown-wrap-or-insert delim delim 'word nil nil)))))

(defun markdown-insert-italic ()
  "Insert markup to make a region or word italic.
If there is an active region, make the region italic.  If the point
is at a non-italic word, make the word italic.  If the point is at an
italic word or phrase, remove the italic markup.  Otherwise, simply
insert italic delimiters and place the cursor in between them."
  (interactive)
  (let ((delim (if markdown-italic-underscore "_" "*")))
    (if (markdown-use-region-p)
        ;; Active region
        (let ((bounds (markdown-unwrap-things-in-region
                       (region-beginning) (region-end)
                       markdown-regex-italic 1 3)))
          (markdown-wrap-or-insert delim delim nil (car bounds) (cdr bounds)))
      ;; Italic markup removal, italic word at point, or empty markup insertion
      (if (thing-at-point-looking-at markdown-regex-italic)
          (markdown-unwrap-thing-at-point nil 1 3)
        (markdown-wrap-or-insert delim delim 'word nil nil)))))

(defun markdown-insert-strike-through ()
  "Insert markup to make a region or word strikethrough.
If there is an active region, make the region strikethrough.  If the point
is at a non-bold word, make the word strikethrough.  If the point is at a
strikethrough word or phrase, remove the strikethrough markup.  Otherwise,
simply insert bold delimiters and place the cursor in between them."
  (interactive)
  (let ((delim "~~"))
    (if (markdown-use-region-p)
        ;; Active region
        (let ((bounds (markdown-unwrap-things-in-region
                       (region-beginning) (region-end)
                       markdown-regex-strike-through 2 4)))
          (markdown-wrap-or-insert delim delim nil (car bounds) (cdr bounds)))
      ;; Strikethrough markup removal, strikethrough word at point, or empty markup insertion
      (if (thing-at-point-looking-at markdown-regex-strike-through)
          (markdown-unwrap-thing-at-point nil 2 4)
        (markdown-wrap-or-insert delim delim 'word nil nil)))))

(defun markdown-insert-code ()
  "Insert markup to make a region or word an inline code fragment.
If there is an active region, make the region an inline code
fragment.  If the point is at a word, make the word an inline
code fragment.  Otherwise, simply insert code delimiters and
place the cursor in between them."
  (interactive)
  (if (markdown-use-region-p)
      ;; Active region
      (let ((bounds (markdown-unwrap-things-in-region
                     (region-beginning) (region-end)
                     markdown-regex-code 1 3)))
        (markdown-wrap-or-insert "`" "`" nil (car bounds) (cdr bounds)))
    ;; Code markup removal, code markup for word, or empty markup insertion
    (if (markdown-inline-code-at-point)
        (markdown-unwrap-thing-at-point nil 0 2)
      (markdown-wrap-or-insert "`" "`" 'word nil nil))))

(defun markdown-insert-kbd ()
  "Insert markup to wrap region or word in <kbd> tags.
If there is an active region, use the region.  If the point is at
a word, use the word.  Otherwise, simply insert <kbd> tags and
place the cursor in between them."
  (interactive)
  (if (markdown-use-region-p)
      ;; Active region
      (let ((bounds (markdown-unwrap-things-in-region
                     (region-beginning) (region-end)
                     markdown-regex-kbd 0 2)))
        (markdown-wrap-or-insert "<kbd>" "</kbd>" nil (car bounds) (cdr bounds)))
    ;; Markup removal, markup for word, or empty markup insertion
    (if (thing-at-point-looking-at markdown-regex-kbd)
        (markdown-unwrap-thing-at-point nil 0 2)
      (markdown-wrap-or-insert "<kbd>" "</kbd>" 'word nil nil))))

(defun markdown-insert-inline-link (text url &optional title)
  "Insert an inline link with TEXT pointing to URL.
Optionally, the user can provide a TITLE."
  (let ((cur (point)))
    (setq title (and title (concat " \"" title "\"")))
    (insert (concat "[" text "](" url title ")"))
    (cond ((not text) (goto-char (+ 1 cur)))
          ((not url) (goto-char (+ 3 (length text) cur))))))

(defun markdown-insert-inline-link-dwim ()
  "Insert an inline link of the form [link](url) at point.
If there is an active region, the text in the region will be used
as the URL, if it appears to be a URL, or else as the link text.
If the point is at a URL, use it to create a new link. If the
point is at a reference link, convert it to an inline link. If
the point is at a word, use the word as the link text. In these
cases, the point will be left at the position for inserting a
URL. If there is no active region and the point is not at word,
simply insert link markup and place the point in the position to
enter link text."
  (interactive)
  (cond
   ;; If there is an active region, remove existing links in the
   ;; region and use resulting region as link text for a new link.
   ((markdown-use-region-p)
    (let* ((bounds (markdown-unwrap-things-in-region
                    (region-beginning) (region-end)
                    markdown-regex-link-inline 0 3))
           (text (buffer-substring (car bounds) (cdr bounds))))
      (delete-region (car bounds) (cdr bounds))
      (markdown-insert-inline-link text nil)))
   ;; If there is an inline link at the point, remove it and add the
   ;; link text to the kill ring.
   ((thing-at-point-looking-at markdown-regex-link-inline)
    (kill-new (match-string 3))
    (delete-region (match-beginning 0) (match-end 0)))
   ;; If there is an angle URL at the point, use it for a new link.
   ((thing-at-point-looking-at markdown-regex-angle-uri)
    (let ((url (match-string 2)))
      (delete-region (match-beginning 0) (match-end 0))
      (markdown-insert-inline-link nil url)))
   ;; If there is a plain URL at the point, use it for a new link.
   ((thing-at-point-looking-at markdown-regex-uri)
    (let ((url (match-string 0)))
      (delete-region (match-beginning 0) (match-end 0))
      (markdown-insert-inline-link nil url)))
   ;; If there is a reference link at point, convert to inline link.
   ((thing-at-point-looking-at markdown-regex-link-reference)
    (let ((beg (match-beginning 0))
          (end (match-end 0))
          (text (match-string 3))
          (url (markdown-link-link)))
      (delete-region beg end)
      (markdown-insert-inline-link text url)))
   ;; Otherwise, insert a link
   (t (let ((bounds (markdown-wrap-or-insert "[" "]()")))
        (when bounds
          (goto-char (- (cdr bounds) 1)))))))

(defun markdown-insert-reference-link (text label &optional url title)
  "Insert a reference link and, optionally, a reference definition.
The link TEXT will be inserted followed by the optional LABEL.
If a URL is given, also insert a definition for the reference
LABEL according to `markdown-reference-location'.  If a TITLE is
given, it will be added to the end of the reference definition
and will be used to populate the title attribute when converted
to XHTML.  If URL is nil, insert only the link portion (for
example, when a reference label is already defined)."
  (insert (concat "[" text "][" label "]"))
  (when url
    (markdown-insert-reference-definition
     (if (string-equal label "") text label)
     url title)))

(defun markdown-insert-reference-definition (label &optional url title)
  "Add definition for reference LABEL with URL and TITLE.
LABEL is a Markdown reference label without square brackets.
URL and TITLE are optional.  When given, the TITLE will
be used to populate the title attribute when converted to XHTML."
  ;; END specifies where to leave the point upon return
  (let ((end (point)))
    (cl-case markdown-reference-location
      (end         (goto-char (point-max)))
      (immediately (markdown-end-of-block))
      (header      (markdown-end-of-defun)))
    (unless (markdown-cur-line-blank-p) (insert "\n"))
    (insert "\n[" label "]: ")
    (if url
        (insert url)
      ;; When no URL is given, leave cursor at END following the colon
      (setq end (point)))
    (when (> (length title) 0)
      (insert " \"" title "\""))
    (unless (looking-at-p "\n")
      (insert "\n"))
    (goto-char end)
    (when url
      (message
       (substitute-command-keys
        "Defined reference [%s], press \\[markdown-jump] to jump there")
       label))))

(defun markdown-insert-reference-link-dwim ()
  "Insert a reference link of the form [text][label] at point.
If there is an active region, the text in the region will be used
as the link text.  If the point is at an inline link, it will be
converted to a reference link.  If the point is at a word, it will
be used as the link text.  Otherwise, the link text will be read from
the minibuffer.  The link label will be read from the minibuffer in
both cases, with completion from the set of currently defined
references.  To create an implicit reference link, press RET to
accept the default, an empty label.  If the entered referenced
label is not defined, additionally prompt for the URL
and (optional) title.  The reference definition is placed at the
location determined by `markdown-reference-location'."
  (interactive)
  (let* ((defined-labels (markdown-get-defined-references))
         (switch (thing-at-point-looking-at markdown-regex-link-inline))
         (bounds (cond ((markdown-use-region-p)
                        (cons (region-beginning) (region-end)))
                       (switch
                        (cons (match-beginning 0) (match-end 0)))
                       (t
                        (markdown-bounds-of-thing-at-point 'word))))
         (text (cond (switch (match-string 3))
                     (bounds (buffer-substring (car bounds) (cdr bounds)))
                     (t (read-string "Link Text: "))))
         (label (completing-read
                 "Link Label (default: none): " defined-labels
                 nil nil nil 'markdown-reference-label-history nil))
         (ref (save-match-data
                (markdown-reference-definition
                 (if (> (length label) 0) label text))))
         (url (cond (ref nil)
                    (switch (match-string 6))
                    (t (read-string "Link URL: "))))
         (title (cond
                 ((= (length url) 0) nil)
                 (switch (if (> (length (match-string 7)) 2)
                             (substring (match-string 7) 1 -1)
                           nil))
                 (t (read-string "Link Title (optional): ")))))
    (when bounds (delete-region (car bounds) (cdr bounds)))
    (markdown-insert-reference-link text label url title)))

(defun markdown-insert-uri ()
  "Insert markup for an inline URI.
If there is an active region, use it as the URI.  If the point is
at a URI, wrap it with angle brackets.  If the point is at an
inline URI, remove the angle brackets.  Otherwise, simply insert
angle brackets place the point between them."
  (interactive)
  (if (markdown-use-region-p)
      ;; Active region
      (let ((bounds (markdown-unwrap-things-in-region
                     (region-beginning) (region-end)
                     markdown-regex-angle-uri 0 2)))
        (markdown-wrap-or-insert "<" ">" nil (car bounds) (cdr bounds)))
    ;; Markup removal, URI at point, or empty markup insertion
    (if (thing-at-point-looking-at markdown-regex-angle-uri)
        (markdown-unwrap-thing-at-point nil 0 2)
      (markdown-wrap-or-insert "<" ">" 'url nil nil))))

(defun markdown-insert-wiki-link ()
  "Insert a wiki link of the form [[WikiLink]].
If there is an active region, use the region as the link text.
If the point is at a word, use the word as the link text.  If
there is no active region and the point is not at word, simply
insert link markup."
  (interactive)
  (if (markdown-use-region-p)
      ;; Active region
      (markdown-wrap-or-insert "[[" "]]" nil (region-beginning) (region-end))
    ;; Markup removal, wiki link at at point, or empty markup insertion
    (if (thing-at-point-looking-at markdown-regex-wiki-link)
        (if (or markdown-wiki-link-alias-first
                (null (match-string 5)))
            (markdown-unwrap-thing-at-point nil 1 3)
          (markdown-unwrap-thing-at-point nil 1 5))
      (markdown-wrap-or-insert "[[" "]]"))))

(defun markdown-insert-image (&optional arg)
  "Insert image markup using region or word as alt text if possible.
If there is an active region, use the region as the alt text.  If the
point is at a word, use the word as the alt text.  In these cases, the
point will be left at the position for inserting a URL.  If there is no
active region and the point is not at word, simply insert image markup and
place the point in the position to enter alt text.  If ARG is nil, insert
inline image markup.  Otherwise, insert reference image markup."
  (interactive "*P")
  (let ((bounds (if arg
                    (markdown-wrap-or-insert "![" "][]")
                  (markdown-wrap-or-insert "![" "]()"))))
    (when bounds
      (goto-char (- (cdr bounds) 1)))))

(defun markdown-insert-reference-image ()
  "Insert reference-style image markup using region or word as alt text.
Calls `markdown-insert-image' with prefix argument."
  (interactive)
  (markdown-insert-image t))

(defun markdown-remove-header ()
  "Remove header markup if point is at a header.
Return bounds of remaining header text if a header was removed
and nil otherwise."
  (interactive "*")
  (or (markdown-unwrap-thing-at-point markdown-regex-header-atx 0 2)
      (markdown-unwrap-thing-at-point markdown-regex-header-setext 0 1)))

(defun markdown-insert-header (&optional level text setext)
  "Insert or replace header markup.
The level of the header is specified by LEVEL and header text is
given by TEXT.  LEVEL must be an integer from 1 and 6, and the
default value is 1.
When TEXT is nil, the header text is obtained as follows.
If there is an active region, it is used as the header text.
Otherwise, the current line will be used as the header text.
If there is not an active region and the point is at a header,
remove the header markup and replace with level N header.
Otherwise, insert empty header markup and place the cursor in
between.
The style of the header will be atx (hash marks) unless
SETEXT is non-nil, in which case a setext-style (underlined)
header will be inserted."
  (interactive "p\nsHeader text: ")
  (setq level (min (max (or level 1) 1) (if setext 2 6)))
  ;; Determine header text if not given
  (when (null text)
    (if (markdown-use-region-p)
        ;; Active region
        (setq text (delete-and-extract-region (region-beginning) (region-end)))
      ;; No active region
      (markdown-remove-header)
      (setq text (delete-and-extract-region
                  (line-beginning-position) (line-end-position)))
      (when (and setext (string-match-p "^[ \t]*$" text))
        (setq text (read-string "Header text: "))))
    (setq text (markdown-compress-whitespace-string text)))
  ;; Insertion with given text
  (markdown-ensure-blank-line-before)
  (let (hdr)
    (cond (setext
           (setq hdr (make-string (string-width text) (if (= level 2) ?- ?=)))
           (insert text "\n" hdr))
          (t
           (setq hdr (make-string level ?#))
           (insert hdr " " text)
           (when (null markdown-asymmetric-header) (insert " " hdr)))))
  (markdown-ensure-blank-line-after)
  ;; Leave point at end of text
  (cond (setext
         (backward-char (1+ (string-width text))))
        ((null markdown-asymmetric-header)
         (backward-char (1+ level)))))

(defun markdown-insert-header-dwim (&optional arg setext)
  "Insert or replace header markup.
The level and type of the header are determined automatically by
the type and level of the previous header, unless a prefix
argument is given via ARG.
With a numeric prefix valued 1 to 6, insert a header of the given
level, with the type being determined automatically (note that
only level 1 or 2 setext headers are possible).

With a \\[universal-argument] prefix (i.e., when ARG is (4)),
promote the heading by one level.
With two \\[universal-argument] prefixes (i.e., when ARG is (16)),
demote the heading by one level.
When SETEXT is non-nil, prefer setext-style headers when
possible (levels one and two).

When there is an active region, use it for the header text.  When
the point is at an existing header, change the type and level
according to the rules above.
Otherwise, if the line is not empty, create a header using the
text on the current line as the header text.
Finally, if the point is on a blank line, insert empty header
markup (atx) or prompt for text (setext).
See `markdown-insert-header' for more details about how the
header text is determined."
  (interactive "*P")
  (let (level)
    (save-excursion
      (when (or (thing-at-point-looking-at markdown-regex-header)
                (re-search-backward markdown-regex-header nil t))
        ;; level of current or previous header
        (setq level (markdown-outline-level))
        ;; match group 1 indicates a setext header
        (setq setext (match-end 1))))
    ;; check prefix argument
    (cond
     ((and (equal arg '(4)) level (> level 1)) ;; C-u
      (cl-decf level))
     ((and (equal arg '(16)) level (< level 6)) ;; C-u C-u
      (cl-incf level))
     (arg ;; numeric prefix
      (setq level (prefix-numeric-value arg))))
    ;; setext headers must be level one or two
    (and level (setq setext (and setext (<= level 2))))
    ;; insert the heading
    (markdown-insert-header level nil setext)))

(defun markdown-insert-header-setext-dwim (&optional arg)
  "Insert or replace header markup, with preference for setext.
See `markdown-insert-header-dwim' for details, including how ARG is handled."
  (interactive "*P")
  (markdown-insert-header-dwim arg t))

(defun markdown-insert-header-atx-1 ()
  "Insert a first level atx-style (hash mark) header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 1 nil nil))

(defun markdown-insert-header-atx-2 ()
  "Insert a level two atx-style (hash mark) header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 2 nil nil))

(defun markdown-insert-header-atx-3 ()
  "Insert a level three atx-style (hash mark) header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 3 nil nil))

(defun markdown-insert-header-atx-4 ()
  "Insert a level four atx-style (hash mark) header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 4 nil nil))

(defun markdown-insert-header-atx-5 ()
  "Insert a level five atx-style (hash mark) header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 5 nil nil))

(defun markdown-insert-header-atx-6 ()
  "Insert a sixth level atx-style (hash mark) header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 6 nil nil))

(defun markdown-insert-header-setext-1 ()
  "Insert a setext-style (underlined) first-level header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 1 nil t))

(defun markdown-insert-header-setext-2 ()
  "Insert a setext-style (underlined) second-level header.
See `markdown-insert-header'."
  (interactive "*")
  (markdown-insert-header 2 nil t))

(defun markdown-blockquote-indentation (loc)
  "Return string containing necessary indentation for a blockquote at LOC.
Also see `markdown-pre-indentation'."
  (save-excursion
    (goto-char loc)
    (let* ((list-level (length (markdown-calculate-list-levels)))
           (indent ""))
      (dotimes (_ list-level indent)
        (setq indent (concat indent "    "))))))

(defun markdown-insert-blockquote ()
  "Start a blockquote section (or blockquote the region).
If Transient Mark mode is on and a region is active, it is used as
the blockquote text."
  (interactive)
  (if (markdown-use-region-p)
      (markdown-blockquote-region (region-beginning) (region-end))
    (markdown-ensure-blank-line-before)
    (insert (markdown-blockquote-indentation (point)) "> ")
    (markdown-ensure-blank-line-after)))

(defun markdown-block-region (beg end prefix)
  "Format the region using a block prefix.
Arguments BEG and END specify the beginning and end of the
region.  The characters PREFIX will appear at the beginning
of each line."
  (save-excursion
    (let* ((end-marker (make-marker))
           (beg-marker (make-marker)))
      ;; Ensure blank line after and remove extra whitespace
      (goto-char end)
      (skip-syntax-backward "-")
      (set-marker end-marker (point))
      (delete-horizontal-space)
      (markdown-ensure-blank-line-after)
      ;; Ensure blank line before and remove extra whitespace
      (goto-char beg)
      (skip-syntax-forward "-")
      (delete-horizontal-space)
      (markdown-ensure-blank-line-before)
      (set-marker beg-marker (point))
      ;; Insert PREFIX before each line
      (goto-char beg-marker)
      (while (and (< (line-beginning-position) end-marker)
                  (not (eobp)))
        (insert prefix)
        (forward-line)))))

(defun markdown-blockquote-region (beg end)
  "Blockquote the region.
Arguments BEG and END specify the beginning and end of the region."
  (interactive "*r")
  (markdown-block-region
   beg end (concat (markdown-blockquote-indentation
                    (max (point-min) (1- beg))) "> ")))

(defun markdown-pre-indentation (loc)
  "Return string containing necessary whitespace for a pre block at LOC.
Also see `markdown-blockquote-indentation'."
  (save-excursion
    (goto-char loc)
    (let* ((list-level (length (markdown-calculate-list-levels)))
           indent)
      (dotimes (_ (1+ list-level) indent)
        (setq indent (concat indent "    "))))))

(defun markdown-insert-pre ()
  "Start a preformatted section (or apply to the region).
If Transient Mark mode is on and a region is active, it is marked
as preformatted text."
  (interactive)
  (if (markdown-use-region-p)
      (markdown-pre-region (region-beginning) (region-end))
    (markdown-ensure-blank-line-before)
    (insert (markdown-pre-indentation (point)))
    (markdown-ensure-blank-line-after)))

(defun markdown-pre-region (beg end)
  "Format the region as preformatted text.
Arguments BEG and END specify the beginning and end of the region."
  (interactive "*r")
  (let ((indent (markdown-pre-indentation (max (point-min) (1- beg)))))
    (markdown-block-region beg end indent)))

(defun markdown-electric-backquote (arg)
  "Insert a backquote.
The numeric prefix argument ARG says how many times to repeat the insertion.
Call `markdown-insert-gfm-code-block' interactively
if three backquotes inserted at the beginning of line."
  (interactive "*P")
  (self-insert-command (prefix-numeric-value arg))
  (when (and markdown-gfm-use-electric-backquote (looking-back "^```" nil))
    (replace-match "")
    (call-interactively #'markdown-insert-gfm-code-block)))

(defconst markdown-gfm-recognized-languages
  ;; to reproduce/update, evaluate the let-form in
  ;; scripts/get-recognized-gfm-languages.el. that produces a single long sexp,
  ;; but with appropriate use of a keyboard macro, indenting and filling it
  ;; properly is pretty fast.
  '("ABAP" "AGS-Script" "AMPL" "ANTLR" "API-Blueprint" "APL" "ASP" "ATS"
    "ActionScript" "Ada" "Agda" "Alloy" "Ant-Build-System" "ApacheConf" "Apex"
    "AppleScript" "Arc" "Arduino" "AsciiDoc" "AspectJ" "Assembly" "Augeas"
    "AutoHotkey" "AutoIt" "Awk" "Batchfile" "Befunge" "Bison" "BitBake"
    "BlitzBasic" "BlitzMax" "Bluespec" "Boo" "Brainfuck" "Brightscript" "Bro" "C#"
    "C++" "C-ObjDump" "C2hs-Haskell" "CLIPS" "CMake" "COBOL" "CSS" "Cap'n-Proto"
    "CartoCSS" "Ceylon" "Chapel" "Charity" "ChucK" "Cirru" "Clarion" "Clean"
    "Click" "Clojure" "CoffeeScript" "ColdFusion" "ColdFusion-CFC" "Common-Lisp"
    "Component-Pascal" "Cool" "Coq" "Cpp-ObjDump" "Creole" "Crystal" "Cucumber"
    "Cuda" "Cycript" "Cython" "D-ObjDump" "DIGITAL-Command-Language" "DM"
    "DNS-Zone" "DTrace" "Darcs-Patch" "Dart" "Diff" "Dockerfile" "Dogescript"
    "Dylan" "ECL" "ECLiPSe" "Eagle" "Ecere-Projects" "Eiffel" "Elixir" "Elm"
    "Emacs-Lisp" "EmberScript" "Erlang" "F#" "FLUX" "FORTRAN" "Factor" "Fancy"
    "Fantom" "Filterscript" "Formatted" "Forth" "FreeMarker" "Frege" "G-code"
    "GAMS" "GAP" "GAS" "GDScript" "GLSL" "Game-Maker-Language" "Genshi"
    "Gentoo-Ebuild" "Gentoo-Eclass" "Gettext-Catalog" "Glyph" "Gnuplot" "Go"
    "Golo" "Gosu" "Grace" "Gradle" "Grammatical-Framework"
    "Graph-Modeling-Language" "Graphviz-(DOT)" "Groff" "Groovy"
    "Groovy-Server-Pages" "HCL" "HTML" "HTML+Django" "HTML+EEX" "HTML+ERB"
    "HTML+PHP" "HTTP" "Hack" "Haml" "Handlebars" "Harbour" "Haskell" "Haxe" "Hy"
    "HyPhy" "IDL" "IGOR-Pro" "INI" "IRC-log" "Idris" "Inform-7" "Inno-Setup" "Io"
    "Ioke" "Isabelle" "Isabelle-ROOT" "JFlex" "JSON" "JSON5" "JSONLD" "JSONiq"
    "JSX" "Jade" "Jasmin" "Java" "Java-Server-Pages" "JavaScript" "Julia"
    "Jupyter-Notebook" "KRL" "KiCad" "Kit" "Kotlin" "LFE" "LLVM" "LOLCODE" "LSL"
    "LabVIEW" "Lasso" "Latte" "Lean" "Less" "Lex" "LilyPond" "Limbo"
    "Linker-Script" "Linux-Kernel-Module" "Liquid" "Literate-Agda"
    "Literate-CoffeeScript" "Literate-Haskell" "LiveScript" "Logos" "Logtalk"
    "LookML" "LoomScript" "Lua" "MAXScript" "MTML" "MUF" "Makefile" "Mako"
    "Markdown" "Mask" "Mathematica" "Matlab" "Maven-POM" "Max" "MediaWiki"
    "Mercury" "Metal" "MiniD" "Mirah" "Modelica" "Modula-2"
    "Module-Management-System" "Monkey" "Moocode" "MoonScript" "Myghty" "NCL" "NL"
    "NSIS" "Nemerle" "NetLinx" "NetLinx+ERB" "NetLogo" "NewLisp" "Nginx" "Nimrod"
    "Ninja" "Nit" "Nix" "Nu" "NumPy" "OCaml" "ObjDump" "Objective-C"
    "Objective-C++" "Objective-J" "Omgrofl" "Opa" "Opal" "OpenCL" "OpenEdge-ABL"
    "OpenSCAD" "Org" "Ox" "Oxygene" "Oz" "PAWN" "PHP" "PLSQL" "PLpgSQL" "Pan"
    "Papyrus" "Parrot" "Parrot-Assembly" "Parrot-Internal-Representation" "Pascal"
    "Perl" "Perl6" "Pickle" "PicoLisp" "PigLatin" "Pike" "Pod" "PogoScript" "Pony"
    "PostScript" "PowerShell" "Processing" "Prolog" "Propeller-Spin"
    "Protocol-Buffer" "Public-Key" "Puppet" "Pure-Data" "PureBasic" "PureScript"
    "Python" "Python-traceback" "QML" "QMake" "RAML" "RDoc" "REALbasic" "RHTML"
    "RMarkdown" "Racket" "Ragel-in-Ruby-Host" "Raw-token-data" "Rebol" "Red"
    "Redcode" "Ren'Py" "RenderScript" "RobotFramework" "Rouge" "Ruby" "Rust" "SAS"
    "SCSS" "SMT" "SPARQL" "SQF" "SQL" "SQLPL" "STON" "SVG" "Sage" "SaltStack"
    "Sass" "Scala" "Scaml" "Scheme" "Scilab" "Self" "Shell" "ShellSession" "Shen"
    "Slash" "Slim" "Smali" "Smalltalk" "Smarty" "SourcePawn" "Squirrel" "Stan"
    "Standard-ML" "Stata" "Stylus" "SuperCollider" "Swift" "SystemVerilog" "TOML"
    "TXL" "Tcl" "Tcsh" "TeX" "Tea" "Text" "Textile" "Thrift" "Turing" "Turtle"
    "Twig" "TypeScript" "Unified-Parallel-C" "Unity3D-Asset" "UnrealScript"
    "UrWeb" "VCL" "VHDL" "Vala" "Verilog" "VimL" "Visual-Basic" "Volt" "Vue"
    "Web-Ontology-Language" "WebIDL" "X10" "XC" "XML" "XPages" "XProc" "XQuery"
    "XS" "XSLT" "Xojo" "Xtend" "YAML" "Yacc" "Zephir" "Zimpl" "desktop" "eC" "edn"
    "fish" "mupad" "nesC" "ooc" "reStructuredText" "wisp" "xBase")
  "Language specifiers recognized by GitHub's syntax highlighting features.")

(defvar markdown-gfm-used-languages nil
  "Language names used in GFM code blocks.")
(make-variable-buffer-local 'markdown-gfm-used-languages)

(defun markdown-trim-whitespace (str)
  (markdown-replace-regexp-in-string
   "\\(?:[[:space:]\r\n]+\\'\\|\\`[[:space:]\r\n]+\\)" "" str))

(defun markdown-clean-language-string (str)
  (markdown-replace-regexp-in-string
   "{\\.?\\|}" "" (markdown-trim-whitespace str)))

(defun markdown-validate-language-string (widget)
  (let ((str (widget-value widget)))
    (unless (string= str (markdown-clean-language-string str))
      (widget-put widget :error (format "Invalid language spec: '%s'" str))
      widget)))

(defun markdown-gfm-get-corpus ()
  "Create corpus of recognized GFM code block languages for the given buffer."
  (let ((given-corpus (append markdown-gfm-additional-languages
                              markdown-gfm-recognized-languages)))
    (append
     markdown-gfm-used-languages
     (if markdown-gfm-downcase-languages (cl-mapcar #'downcase given-corpus)
       given-corpus))))

(defun markdown-gfm-add-used-language (lang)
  "Clean LANG and add to list of used languages."
  (setq markdown-gfm-used-languages
          (cons lang (remove lang markdown-gfm-used-languages))))

(defun markdown-insert-gfm-code-block (&optional lang)
  "Insert GFM code block for language LANG.
If LANG is nil, the language will be queried from user.  If a
region is active, wrap this region with the markup instead.  If
the region boundaries are not on empty lines, these are added
automatically in order to have the correct markup."
  (interactive
   (list (let ((completion-ignore-case nil))
           (condition-case nil
               (markdown-clean-language-string
                (completing-read
                 "Programming language: "
                 (markdown-gfm-get-corpus)
                 nil 'confirm (car markdown-gfm-used-languages)
                 'markdown-gfm-language-history))
             (quit "")))))
  (unless (string= lang "") (markdown-gfm-add-used-language lang))
  (when (> (length lang) 0) (setq lang (concat " " lang)))
  (if (markdown-use-region-p)
      (let ((b (region-beginning)) (e (region-end)))
        (goto-char e)
        ;; if we're on a blank line, don't newline, otherwise the ```
        ;; should go on its own line
        (unless (looking-back "\n" nil)
          (newline))
        (insert "```")
        (markdown-ensure-blank-line-after)
        (goto-char b)
        ;; if we're on a blank line, insert the quotes here, otherwise
        ;; add a new line first
        (unless (looking-at-p "\n")
          (newline)
          (forward-line -1))
        (markdown-ensure-blank-line-before)
        (insert "```" lang))
    (markdown-ensure-blank-line-before)
    (insert "```" lang "\n\n```")
    (markdown-ensure-blank-line-after)
    (forward-line -1)))

(defun markdown-gfm-parse-buffer-for-languages (&optional buffer)
  (with-current-buffer (or buffer (current-buffer))
    (save-excursion
      (goto-char (point-min))
      (cl-loop
       with prop = 'markdown-gfm-block-begin
       for pos-prop = (markdown-find-next-prop prop)
       while pos-prop
       for lang = (progn
                    (goto-char (car pos-prop))
                    (save-match-data
                      (set-match-data (get-text-property (point) prop))
                      (when (and (match-beginning 2) (match-end 2))
                        (buffer-substring-no-properties
                         (match-beginning 2) (match-end 2)))))
       do (progn (when lang (markdown-gfm-add-used-language lang))
                 (goto-char (next-single-property-change (point) prop)))))))

\f
;;; Footnotes ==================================================================

(defun markdown-footnote-counter-inc ()
  "Increment `markdown-footnote-counter' and return the new value."
  (when (= markdown-footnote-counter 0) ; hasn't been updated in this buffer yet.
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward (concat "^\\[\\^\\(" markdown-footnote-chars "*?\\)\\]:")
                                (point-max) t)
        (let ((fn (string-to-number (match-string 1))))
          (when (> fn markdown-footnote-counter)
            (setq markdown-footnote-counter fn))))))
  (cl-incf markdown-footnote-counter))

(defun markdown-insert-footnote ()
  "Insert footnote with a new number and move point to footnote definition."
  (interactive)
  (let ((fn (markdown-footnote-counter-inc)))
    (insert (format "[^%d]" fn))
    (markdown-footnote-text-find-new-location)
    (markdown-ensure-blank-line-before)
    (unless (markdown-cur-line-blank-p)
      (insert "\n"))
    (insert (format "[^%d]: " fn))
    (markdown-ensure-blank-line-after)))

(defun markdown-footnote-text-find-new-location ()
  "Position the cursor at the proper location for a new footnote text."
  (cond
   ((eq markdown-footnote-location 'end) (goto-char (point-max)))
   ((eq markdown-footnote-location 'immediately) (markdown-end-of-block))
   ((eq markdown-footnote-location 'header) (markdown-end-of-defun))))

(defun markdown-footnote-kill ()
  "Kill the footnote at point.
The footnote text is killed (and added to the kill ring), the
footnote marker is deleted.  Point has to be either at the
footnote marker or in the footnote text."
  (interactive)
  (let ((marker-pos nil)
        (skip-deleting-marker nil)
        (starting-footnote-text-positions
         (markdown-footnote-text-positions)))
    (when starting-footnote-text-positions
      ;; We're starting in footnote text, so mark our return position and jump
      ;; to the marker if possible.
      (let ((marker-pos (markdown-footnote-find-marker
                         (cl-first starting-footnote-text-positions))))
        (if marker-pos
            (goto-char (1- marker-pos))
          ;; If there isn't a marker, we still want to kill the text.
          (setq skip-deleting-marker t))))
    ;; Either we didn't start in the text, or we started in the text and jumped
    ;; to the marker. We want to assume we're at the marker now and error if
    ;; we're not.
    (unless skip-deleting-marker
      (let ((marker (markdown-footnote-delete-marker)))
        (unless marker
          (error "Not at a footnote"))
        ;; Even if we knew the text position before, it changed when we deleted
        ;; the label.
        (setq marker-pos (cl-second marker))
        (let ((new-text-pos (markdown-footnote-find-text (cl-first marker))))
          (unless new-text-pos
            (error "No text for footnote `%s'" (cl-first marker)))
          (goto-char new-text-pos))))
    (let ((pos (markdown-footnote-kill-text)))
      (goto-char (if starting-footnote-text-positions
                     pos
                   marker-pos)))))

(defun markdown-footnote-delete-marker ()
  "Delete a footnote marker at point.
Returns a list (ID START) containing the footnote ID and the
start position of the marker before deletion.  If no footnote
marker was deleted, this function returns NIL."
  (let ((marker (markdown-footnote-marker-positions)))
    (when marker
      (delete-region (cl-second marker) (cl-third marker))
      (butlast marker))))

(defun markdown-footnote-kill-text ()
  "Kill footnote text at point.
Returns the start position of the footnote text before deletion,
or NIL if point was not inside a footnote text.

The killed text is placed in the kill ring (without the footnote
number)."
  (let ((fn (markdown-footnote-text-positions)))
    (when fn
      (let ((text (delete-and-extract-region (cl-second fn) (cl-third fn))))
        (string-match (concat "\\[\\" (cl-first fn) "\\]:[[:space:]]*\\(\\(.*\n?\\)*\\)") text)
        (kill-new (match-string 1 text))
        (when (and (markdown-cur-line-blank-p)
                   (markdown-prev-line-blank-p)
                   (not (bobp)))
          (delete-region (1- (point)) (point)))
        (cl-second fn)))))

(defun markdown-footnote-goto-text ()
  "Jump to the text of the footnote at point."
  (interactive)
  (let ((fn (car (markdown-footnote-marker-positions))))
    (unless fn
      (error "Not at a footnote marker"))
    (let ((new-pos (markdown-footnote-find-text fn)))
      (unless new-pos
        (error "No definition found for footnote `%s'" fn))
      (goto-char new-pos))))

(defun markdown-footnote-return ()
  "Return from a footnote to its footnote number in the main text."
  (interactive)
  (let ((fn (save-excursion
              (car (markdown-footnote-text-positions)))))
    (unless fn
      (error "Not in a footnote"))
    (let ((new-pos (markdown-footnote-find-marker fn)))
      (unless new-pos
        (error "Footnote marker `%s' not found" fn))
      (goto-char new-pos))))

(defun markdown-footnote-find-marker (id)
  "Find the location of the footnote marker with ID.
The actual buffer position returned is the position directly
following the marker's closing bracket.  If no marker is found,
NIL is returned."
  (save-excursion
    (goto-char (point-min))
    (when (re-search-forward (concat "\\[" id "\\]\\([^:]\\|\\'\\)") nil t)
      (skip-chars-backward "^]")
      (point))))

(defun markdown-footnote-find-text (id)
  "Find the location of the text of footnote ID.
The actual buffer position returned is the position of the first
character of the text, after the footnote's identifier.  If no
footnote text is found, NIL is returned."
  (save-excursion
    (goto-char (point-min))
    (when (re-search-forward (concat "^\\[" id "\\]:") nil t)
      (skip-chars-forward "[ \t]")
      (point))))

(defun markdown-footnote-marker-positions ()
  "Return the position and ID of the footnote marker point is on.
The return value is a list (ID START END).  If point is not on a
footnote, NIL is returned."
  ;; first make sure we're at a footnote marker
  (if (or (looking-back (concat "\\[\\^" markdown-footnote-chars "*\\]?") (line-beginning-position))
          (looking-at-p (concat "\\[?\\^" markdown-footnote-chars "*?\\]")))
      (save-excursion
        ;; move point between [ and ^:
        (if (looking-at-p "\\[")
            (forward-char 1)
          (skip-chars-backward "^["))
        (looking-at (concat "\\(\\^" markdown-footnote-chars "*?\\)\\]"))
        (list (match-string 1) (1- (match-beginning 1)) (1+ (match-end 1))))))

(defun markdown-footnote-text-positions ()
  "Return the start and end positions of the footnote text point is in.
The exact return value is a list of three elements: (ID START END).
The start position is the position of the opening bracket
of the footnote id.  The end position is directly after the
newline that ends the footnote.  If point is not in a footnote,
NIL is returned instead."
  (save-excursion
    (let (result)
      (move-beginning-of-line 1)
      ;; Try to find the label. If we haven't found the label and we're at a blank
      ;; or indented line, back up if possible.
      (while (and
              (not (and (looking-at markdown-regex-footnote-definition)
                        (setq result (list (match-string 1) (point)))))
              (and (not (bobp))
                   (or (markdown-cur-line-blank-p)
                       (>= (current-indentation) 4))))
        (forward-line -1))
      (when result
        ;; Advance if there is a next line that is either blank or indented.
        ;; (Need to check if we're on the last line, because
        ;; markdown-next-line-blank-p returns true for last line in buffer.)
        (while (and (/= (line-end-position) (point-max))
                    (or (markdown-next-line-blank-p)
                        (>= (markdown-next-line-indent) 4)))
          (forward-line))
        ;; Move back while the current line is blank.
        (while (markdown-cur-line-blank-p)
          (forward-line -1))
        ;; Advance to capture this line and a single trailing newline (if there
        ;; is one).
        (forward-line)
        (append result (list (point)))))))

\f
;;; Element Removal ===========================================================

(defun markdown-kill-thing-at-point ()
  "Kill thing at point and add important text, without markup, to kill ring.
Possible things to kill include (roughly in order of precedence):
inline code, headers, horizonal rules, links (add link text to
kill ring), images (add alt text to kill ring), angle uri, email
addresses, bold, italics, reference definition (add URI to kill
ring), footnote markers and text (kill both marker and text, add
text to kill ring), and list items."
  (interactive "*")
  (let (val)
    (cond
     ;; Inline code
     ((markdown-inline-code-at-point)
      (kill-new (match-string 2))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; ATX header
     ((thing-at-point-looking-at markdown-regex-header-atx)
      (kill-new (match-string 2))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Setext header
     ((thing-at-point-looking-at markdown-regex-header-setext)
      (kill-new (match-string 1))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Horizonal rule
     ((thing-at-point-looking-at markdown-regex-hr)
      (kill-new (match-string 0))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Inline link or image (add link or alt text to kill ring)
     ((thing-at-point-looking-at markdown-regex-link-inline)
      (kill-new (match-string 3))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Reference link or image (add link or alt text to kill ring)
     ((thing-at-point-looking-at markdown-regex-link-reference)
      (kill-new (match-string 3))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Angle URI (add URL to kill ring)
     ((thing-at-point-looking-at markdown-regex-angle-uri)
      (kill-new (match-string 2))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Email address in angle brackets (add email address to kill ring)
     ((thing-at-point-looking-at markdown-regex-email)
      (kill-new (match-string 1))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; Wiki link (add alias text to kill ring)
     ((and markdown-enable-wiki-links
           (thing-at-point-looking-at markdown-regex-wiki-link))
      (kill-new (markdown-wiki-link-alias))
      (delete-region (match-beginning 1) (match-end 1)))
     ;; Bold
     ((thing-at-point-looking-at markdown-regex-bold)
      (kill-new (match-string 4))
      (delete-region (match-beginning 2) (match-end 2)))
     ;; Italics
     ((thing-at-point-looking-at markdown-regex-italic)
      (kill-new (match-string 3))
      (delete-region (match-beginning 1) (match-end 1)))
     ;; Strikethrough
     ((thing-at-point-looking-at markdown-regex-strike-through)
      (kill-new (match-string 4))
      (delete-region (match-beginning 2) (match-end 2)))
     ;; Footnote marker (add footnote text to kill ring)
     ((thing-at-point-looking-at markdown-regex-footnote)
      (markdown-footnote-kill))
     ;; Footnote text (add footnote text to kill ring)
     ((setq val (markdown-footnote-text-positions))
      (markdown-footnote-kill))
     ;; Reference definition (add URL to kill ring)
     ((thing-at-point-looking-at markdown-regex-reference-definition)
      (kill-new (match-string 5))
      (delete-region (match-beginning 0) (match-end 0)))
     ;; List item
     ((setq val (markdown-cur-list-item-bounds))
      (kill-new (delete-and-extract-region (cl-first val) (cl-second val))))
     (t
      (error "Nothing found at point to kill")))))

\f
;;; Indentation ====================================================================

(defun markdown-indent-find-next-position (cur-pos positions)
  "Return the position after the index of CUR-POS in POSITIONS.
Positions are calculated by `markdown-calc-indents'."
  (while (and positions
              (not (equal cur-pos (car positions))))
    (setq positions (cdr positions)))
  (or (cadr positions) 0))

(defun markdown-exdent-find-next-position (cur-pos positions)
  "Return the maximal element that precedes CUR-POS from POSITIONS.
Positions are calculated by `markdown-calc-indents'."
  (let ((result 0))
    (dolist (i positions)
      (when (< i cur-pos)
        (setq result (max result i))))
    result))

(defun markdown-indent-line ()
  "Indent the current line using some heuristics.
If the _previous_ command was either `markdown-enter-key' or
`markdown-cycle', then we should cycle to the next
reasonable indentation position.  Otherwise, we could have been
called directly by `markdown-enter-key', by an initial call of
`markdown-cycle', or indirectly by `auto-fill-mode'.  In
these cases, indent to the default position.
Positions are calculated by `markdown-calc-indents'."
  (interactive)
  (let ((positions (markdown-calc-indents))
        (cursor-pos (current-column))
        (_ (back-to-indentation))
        (cur-pos (current-column)))
    (if (not (equal this-command 'markdown-cycle))
        (indent-line-to (car positions))
      (setq positions (sort (delete-dups positions) '<))
      (let* ((next-pos (markdown-indent-find-next-position cur-pos positions))
             (new-cursor-pos
              (if (< cur-pos next-pos)
                  (+ cursor-pos (- next-pos cur-pos))
                (- cursor-pos cur-pos))))
        (indent-line-to next-pos)
        (move-to-column new-cursor-pos)))))

(defun markdown-calc-indents ()
  "Return a list of indentation columns to cycle through.
The first element in the returned list should be considered the
default indentation level.  This function does not worry about
duplicate positions, which are handled up by calling functions."
  (let (pos prev-line-pos positions)

    ;; Indentation of previous line
    (setq prev-line-pos (markdown-prev-line-indent))
    (setq positions (cons prev-line-pos positions))

    ;; Indentation of previous non-list-marker text
    (when (setq pos (markdown-prev-non-list-indent))
      (setq positions (cons pos positions)))

    ;; Indentation required for a pre block in current context
    (setq pos (length (markdown-pre-indentation (point))))
    (setq positions (cons pos positions))

    ;; Indentation of the previous line + tab-width
    (if prev-line-pos
        (setq positions (cons (+ prev-line-pos tab-width) positions))
      (setq positions (cons tab-width positions)))

    ;; Indentation of the previous line - tab-width
    (if (and prev-line-pos (> prev-line-pos tab-width))
        (setq positions (cons (- prev-line-pos tab-width) positions)))

    ;; Indentation of all preceeding list markers (when in a list)
    (when (setq pos (markdown-calculate-list-levels))
      (setq positions (append pos positions)))

    ;; First column
    (setq positions (cons 0 positions))

    ;; Return reversed list
    (reverse positions)))

(defun markdown-enter-key ()
  "Handle RET according to customized settings.
When `markdown-indent-on-enter' is nil, this is equivalent to
`newline'.  Otherwise, indent following RET and when the point is
in a list item, start a new item with the same indentation.  If
the point is in an empty list item, remove it."
  (interactive)
  (if (not markdown-indent-on-enter)
      (newline)
    (let ((bounds (markdown-cur-list-item-bounds)))
      (if bounds
          (let ((beg (cl-first bounds))
                (end (cl-second bounds))
                (length (cl-fourth bounds)))
            ;; Point is in a list item
            (if (= (- end beg) length)
                ;; Delete blank list
                (progn
                  (delete-region beg end)
                  (newline)
                  (markdown-indent-line))
              (call-interactively #'markdown-insert-list-item)))
        ;; Point is not in a list
        (newline)
        (markdown-indent-line)))))

(defun markdown-exdent-or-delete (arg)
  "Handle BACKSPACE by cycling through indentation points.
When BACKSPACE is pressed, if there is only whitespace
before the current point, then exdent the line one level.
Otherwise, do normal delete by repeating
`backward-delete-char-untabify' ARG times."
  (interactive "*p")
  (if (use-region-p)
      (backward-delete-char-untabify arg)
    (let ((cur-pos (current-column))
          (start-of-indention (save-excursion
                                (back-to-indentation)
                                (current-column)))
          (positions (markdown-calc-indents)))
      (if (and (> cur-pos 0) (= cur-pos start-of-indention))
          (indent-line-to (markdown-exdent-find-next-position cur-pos positions))
        (backward-delete-char-untabify arg)))))

(defun markdown-find-leftmost-column (beg end)
  "Find the leftmost column in the region from BEG to END."
  (let ((mincol 1000))
    (save-excursion
      (goto-char beg)
      (while (< (point) end)
        (back-to-indentation)
        (unless (looking-at-p "[ \t]*$")
          (setq mincol (min mincol (current-column))))
        (forward-line 1)
        ))
    mincol))

(defun markdown-indent-region (beg end arg)
  "Indent the region from BEG to END using some heuristics.
When ARG is non-nil, exdent the region instead.
See `markdown-indent-line' and `markdown-indent-line'."
  (interactive "*r\nP")
  (let* ((positions (sort (delete-dups (markdown-calc-indents)) '<))
         (leftmostcol (markdown-find-leftmost-column beg end))
         (next-pos (if arg
                       (markdown-exdent-find-next-position leftmostcol positions)
                     (markdown-indent-find-next-position leftmostcol positions))))
    (indent-rigidly beg end (- next-pos leftmostcol))
    (setq deactivate-mark nil)))

(defun markdown-exdent-region (beg end)
  "Call `markdown-indent-region' on region from BEG to END with prefix."
  (interactive "*r")
  (markdown-indent-region beg end t))

\f
;;; Markup Completion =========================================================

(defconst markdown-complete-alist
  '((markdown-regex-header-atx . markdown-complete-atx)
    (markdown-regex-header-setext . markdown-complete-setext)
    (markdown-regex-hr . markdown-complete-hr))
  "Association list of form (regexp . function) for markup completion.")

(defun markdown-incomplete-atx-p ()
  "Return t if ATX header markup is incomplete and nil otherwise.
Assumes match data is available for `markdown-regex-header-atx'.
Checks that the number of trailing hash marks equals the number of leading
hash marks, that there is only a single space before and after the text,
and that there is no extraneous whitespace in the text."
  (or
   ;; Number of starting and ending hash marks differs
   (not (= (length (match-string 1)) (length (match-string 3))))
   ;; When the header text is not empty...
   (and (> (length (match-string 2)) 0)
        ;; ...if there are extra leading, trailing, or interior spaces
        (or (not (= (match-beginning 2) (1+ (match-end 1))))
            (not (= (match-beginning 3) (1+ (match-end 2))))
            (string-match-p "[ \t\n]\\{2\\}" (match-string 2))))
   ;; When the header text is empty...
   (and (= (length (match-string 2)) 0)
        ;; ...if there are too many or too few spaces
        (not (= (match-beginning 3) (+ (match-end 1) 2))))))

(defun markdown-complete-atx ()
  "Complete and normalize ATX headers.
Add or remove hash marks to the end of the header to match the
beginning.  Ensure that there is only a single space between hash
marks and header text.  Removes extraneous whitespace from header text.
Assumes match data is available for `markdown-regex-header-atx'.
Return nil if markup was complete and non-nil if markup was completed."
  (when (markdown-incomplete-atx-p)
    (let* ((new-marker (make-marker))
           (new-marker (set-marker new-marker (match-end 2))))
      ;; Hash marks and spacing at end
      (goto-char (match-end 2))
      (delete-region (match-end 2) (match-end 3))
      (insert " " (match-string 1))
      ;; Remove extraneous whitespace from title
      (replace-match (markdown-compress-whitespace-string (match-string 2))
                     t t nil 2)
      ;; Spacing at beginning
      (goto-char (match-end 1))
      (delete-region (match-end 1) (match-beginning 2))
      (insert " ")
      ;; Leave point at end of text
      (goto-char new-marker))))

(defun markdown-incomplete-setext-p ()
  "Return t if setext header markup is incomplete and nil otherwise.
Assumes match data is available for `markdown-regex-header-setext'.
Checks that length of underline matches text and that there is no
extraneous whitespace in the text."
  (or (not (= (length (match-string 1)) (length (match-string 2))))
      (string-match-p "[ \t\n]\\{2\\}" (match-string 1))))

(defun markdown-complete-setext ()
  "Complete and normalize setext headers.
Add or remove underline characters to match length of header
text.  Removes extraneous whitespace from header text.  Assumes
match data is available for `markdown-regex-header-setext'.
Return nil if markup was complete and non-nil if markup was completed."
  (when (markdown-incomplete-setext-p)
    (let* ((text (markdown-compress-whitespace-string (match-string 1)))
           (char (char-after (match-beginning 2)))
           (level (if (char-equal char ?-) 2 1)))
      (goto-char (match-beginning 0))
      (delete-region (match-beginning 0) (match-end 0))
      (markdown-insert-header level text t)
      t)))

(defun markdown-incomplete-hr-p ()
  "Return non-nil if hr is not in `markdown-hr-strings' and nil otherwise.
Assumes match data is available for `markdown-regex-hr'."
  (not (member (match-string 0) markdown-hr-strings)))

(defun markdown-complete-hr ()
  "Complete horizontal rules.
If horizontal rule string is a member of `markdown-hr-strings',
do nothing.  Otherwise, replace with the car of
`markdown-hr-strings'.
Assumes match data is available for `markdown-regex-hr'.
Return nil if markup was complete and non-nil if markup was completed."
  (when (markdown-incomplete-hr-p)
    (replace-match (car markdown-hr-strings))
    t))

(defun markdown-complete ()
  "Complete markup of object near point or in region when active.
Handle all objects in `markdown-complete-alist', in order.
See `markdown-complete-at-point' and `markdown-complete-region'."
  (interactive "*")
  (if (markdown-use-region-p)
      (markdown-complete-region (region-beginning) (region-end))
    (markdown-complete-at-point)))

(defun markdown-complete-at-point ()
  "Complete markup of object near point.
Handle all elements of `markdown-complete-alist' in order."
  (interactive "*")
  (let ((list markdown-complete-alist) found changed)
    (while list
      (let ((regexp (eval (caar list)))
            (function (cdar list)))
        (setq list (cdr list))
        (when (thing-at-point-looking-at regexp)
          (setq found t)
          (setq changed (funcall function))
          (setq list nil))))
    (if found
        (or changed (error "Markup at point is complete"))
      (error "Nothing to complete at point"))))

(defun markdown-complete-region (beg end)
  "Complete markup of objects in region from BEG to END.
Handle all objects in `markdown-complete-alist', in order.  Each
match is checked to ensure that a previous regexp does not also
match."
  (interactive "*r")
  (let ((end-marker (set-marker (make-marker) end))
        previous)
    (dolist (element markdown-complete-alist)
      (let ((regexp (eval (car element)))
            (function (cdr element)))
        (goto-char beg)
        (while (re-search-forward regexp end-marker 'limit)
          (when (match-string 0)
            ;; Make sure this is not a match for any of the preceding regexps.
            ;; This prevents mistaking an HR for a Setext subheading.
            (let (match)
              (save-match-data
                (dolist (prev-regexp previous)
                  (or match (setq match (looking-back prev-regexp nil)))))
              (unless match
                (save-excursion (funcall function))))))
        (cl-pushnew regexp previous :test #'equal)))
    previous))

(defun markdown-complete-buffer ()
  "Complete markup for all objects in the current buffer."
  (interactive "*")
  (markdown-complete-region (point-min) (point-max)))

\f
;;; Markup Cycling ============================================================

(defun markdown-cycle-atx (arg &optional remove)
  "Cycle ATX header markup.
Promote header (decrease level) when ARG is 1 and demote
header (increase level) if arg is -1.  When REMOVE is non-nil,
remove the header when the level reaches zero and stop cycling
when it reaches six.  Otherwise, perform a proper cycling through
levels one through six.  Assumes match data is available for
`markdown-regex-header-atx'."
  (let* ((old-level (length (match-string 1)))
         (new-level (+ old-level arg))
         (text (match-string 2)))
    (when (not remove)
      (setq new-level (% new-level 6))
      (setq new-level (cond ((= new-level 0) 6)
                            ((< new-level 0) (+ new-level 6))
                            (t new-level))))
    (cond
     ((= new-level 0)
      (markdown-unwrap-thing-at-point nil 0 2))
     ((<= new-level 6)
      (goto-char (match-beginning 0))
      (delete-region (match-beginning 0) (match-end 0))
      (markdown-insert-header new-level text nil)))))

(defun markdown-cycle-setext (arg &optional remove)
  "Cycle setext header markup.
Promote header (increase level) when ARG is 1 and demote
header (decrease level or remove) if arg is -1.  When demoting a
level-two setext header, replace with a level-three atx header.
When REMOVE is non-nil, remove the header when the level reaches
zero.  Otherwise, cycle back to a level six atx header.  Assumes
match data is available for `markdown-regex-header-setext'."
  (let* ((char (char-after (match-beginning 2)))
         (old-level (if (char-equal char ?=) 1 2))
         (new-level (+ old-level arg)))
    (when (and (not remove) (= new-level 0))
      (setq new-level 6))
    (cond
     ((= new-level 0)
      (markdown-unwrap-thing-at-point nil 0 1))
     ((<= new-level 2)
      (markdown-insert-header new-level nil t))
     ((<= new-level 6)
      (markdown-insert-header new-level nil nil)))))

(defun markdown-cycle-hr (arg &optional remove)
  "Cycle string used for horizontal rule from `markdown-hr-strings'.
When ARG is 1, cycle forward (demote), and when ARG is -1, cycle
backwards (promote).  When REMOVE is non-nil, remove the hr instead
of cycling when the end of the list is reached.
Assumes match data is available for `markdown-regex-hr'."
  (let* ((strings (if (= arg -1)
                      (reverse markdown-hr-strings)
                    markdown-hr-strings))
         (tail (member (match-string 0) strings))
         (new (or (cadr tail)
                  (if remove
                      (if (= arg 1)
                          ""
                        (car tail))
                    (car strings)))))
    (replace-match new)))

(defun markdown-cycle-bold ()
  "Cycle bold markup between underscores and asterisks.
Assumes match data is available for `markdown-regex-bold'."
  (save-excursion
    (let* ((old-delim (match-string 3))
           (new-delim (if (string-equal old-delim "**") "__" "**")))
      (replace-match new-delim t t nil 3)
      (replace-match new-delim t t nil 5))))

(defun markdown-cycle-italic ()
  "Cycle italic markup between underscores and asterisks.
Assumes match data is available for `markdown-regex-italic'."
  (save-excursion
    (let* ((old-delim (match-string 2))
           (new-delim (if (string-equal old-delim "*") "_" "*")))
      (replace-match new-delim t t nil 2)
      (replace-match new-delim t t nil 4))))

\f
;;; Keymap ====================================================================

(defvar markdown-mode-map
  (let ((map (make-keymap)))
    ;; Element insertion
    (define-key map "\C-c\C-al" 'markdown-insert-inline-link-dwim)
    (define-key map "\C-c\C-aL" 'markdown-insert-reference-link-dwim)
    (define-key map "\C-c\C-au" 'markdown-insert-uri)
    (define-key map "\C-c\C-af" 'markdown-insert-footnote)
    (define-key map "\C-c\C-aw" 'markdown-insert-wiki-link)
    (define-key map "\C-c\C-ii" 'markdown-insert-image)
    (define-key map "\C-c\C-iI" 'markdown-insert-reference-image)
    (define-key map "\C-c\C-i\C-t" 'markdown-toggle-inline-images)
    (define-key map "\C-c\C-th" 'markdown-insert-header-dwim)
    (define-key map "\C-c\C-tH" 'markdown-insert-header-setext-dwim)
    (define-key map "\C-c\C-t1" 'markdown-insert-header-atx-1)
    (define-key map "\C-c\C-t2" 'markdown-insert-header-atx-2)
    (define-key map "\C-c\C-t3" 'markdown-insert-header-atx-3)
    (define-key map "\C-c\C-t4" 'markdown-insert-header-atx-4)
    (define-key map "\C-c\C-t5" 'markdown-insert-header-atx-5)
    (define-key map "\C-c\C-t6" 'markdown-insert-header-atx-6)
    (define-key map "\C-c\C-t!" 'markdown-insert-header-setext-1)
    (define-key map "\C-c\C-t@" 'markdown-insert-header-setext-2)
    (define-key map "\C-c\C-ss" 'markdown-insert-bold)
    (define-key map "\C-c\C-se" 'markdown-insert-italic)
    (define-key map "\C-c\C-sc" 'markdown-insert-code)
    (define-key map "\C-c\C-sb" 'markdown-insert-blockquote)
    (define-key map "\C-c\C-sk" 'markdown-insert-kbd)
    (define-key map "\C-c\C-s\C-b" 'markdown-blockquote-region)
    (define-key map "\C-c\C-sp" 'markdown-insert-pre)
    (define-key map "\C-c\C-s\C-p" 'markdown-pre-region)
    (define-key map "\C-c\C-sP" 'markdown-insert-gfm-code-block)
    (define-key map "\C-c-" 'markdown-insert-hr)
    ;; Element insertion (deprecated)
    (define-key map "\C-c\C-ar" 'markdown-insert-reference-link-dwim)
    (define-key map "\C-c\C-tt" 'markdown-insert-header-setext-1)
    (define-key map "\C-c\C-ts" 'markdown-insert-header-setext-2)
    ;; Element removal
    (define-key map (kbd "C-c C-k") 'markdown-kill-thing-at-point)
    ;; Promotion, Demotion, Completion, and Cycling
    (define-key map (kbd "C-c C--") 'markdown-promote)
    (define-key map (kbd "C-c C-=") 'markdown-demote)
    (define-key map (kbd "C-c C-]") 'markdown-complete)
    ;; Following and Jumping
    (define-key map (kbd "C-c C-o") 'markdown-follow-thing-at-point)
    (define-key map (kbd "C-c C-l") 'markdown-jump)
    ;; Indentation
    (define-key map (kbd "C-m") 'markdown-enter-key)
    (define-key map (kbd "DEL") 'markdown-exdent-or-delete)
    (define-key map (kbd "C-c >") 'markdown-indent-region)
    (define-key map (kbd "C-c <") 'markdown-exdent-region)
    ;; Visibility cycling
    (define-key map (kbd "TAB") 'markdown-cycle)
    (define-key map (kbd "<S-iso-lefttab>") 'markdown-shifttab)
    (define-key map (kbd "<S-tab>")  'markdown-shifttab)
    (define-key map (kbd "<backtab>") 'markdown-shifttab)
    ;; Header navigation
    (define-key map (kbd "C-c C-n") 'markdown-next-visible-heading)
    (define-key map (kbd "C-c C-p") 'markdown-previous-visible-heading)
    (define-key map (kbd "C-c C-f") 'markdown-forward-same-level)
    (define-key map (kbd "C-c C-b") 'markdown-backward-same-level)
    (define-key map (kbd "C-c C-u") 'markdown-up-heading)
    ;; Buffer-wide commands
    (define-key map (kbd "C-c C-c m") 'markdown-other-window)
    (define-key map (kbd "C-c C-c p") 'markdown-preview)
    (define-key map (kbd "C-c C-c e") 'markdown-export)
    (define-key map (kbd "C-c C-c v") 'markdown-export-and-preview)
    (define-key map (kbd "C-c C-c o") 'markdown-open)
    (define-key map (kbd "C-c C-c l") 'markdown-live-preview-mode)
    (define-key map (kbd "C-c C-c w") 'markdown-kill-ring-save)
    (define-key map (kbd "C-c C-c c") 'markdown-check-refs)
    (define-key map (kbd "C-c C-c n") 'markdown-cleanup-list-numbers)
    (define-key map (kbd "C-c C-c ]") 'markdown-complete-buffer)
    ;; List editing
    (define-key map (kbd "M-<up>") 'markdown-move-up)
    (define-key map (kbd "M-<down>") 'markdown-move-down)
    (define-key map (kbd "M-<left>") 'markdown-promote)
    (define-key map (kbd "M-<right>") 'markdown-demote)
    (define-key map (kbd "M-<return>") 'markdown-insert-list-item)
    (define-key map (kbd "C-c C-j") 'markdown-insert-list-item)
    ;; Subtree editing
    (define-key map (kbd "M-S-<up>") 'markdown-move-subtree-up)
    (define-key map (kbd "M-S-<down>") 'markdown-move-subtree-down)
    (define-key map (kbd "M-S-<left>") 'markdown-promote-subtree)
    (define-key map (kbd "M-S-<right>") 'markdown-demote-subtree)
    ;; Movement
    (define-key map (kbd "M-{") 'markdown-backward-paragraph)
    (define-key map (kbd "M-}") 'markdown-forward-paragraph)
    (define-key map (kbd "M-n") 'markdown-next-link)
    (define-key map (kbd "M-p") 'markdown-previous-link)
    ;; Alternative keys (in case of problems with the arrow keys)
    (define-key map (kbd "C-c C-x u") 'markdown-move-up)
    (define-key map (kbd "C-c C-x d") 'markdown-move-down)
    (define-key map (kbd "C-c C-x l") 'markdown-promote)
    (define-key map (kbd "C-c C-x r") 'markdown-demote)
    (define-key map (kbd "C-c C-x m") 'markdown-insert-list-item)
    (define-key map (kbd "C-c C-x C-x") 'markdown-toggle-gfm-checkbox)
    map)
  "Keymap for Markdown major mode.")

(defvar gfm-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map markdown-mode-map)
    (define-key map (kbd "C-c C-s d") 'markdown-insert-strike-through)
    (define-key map "`" 'markdown-electric-backquote)
    map)
  "Keymap for `gfm-mode'.
See also `markdown-mode-map'.")

\f
;;; Menu ==================================================================

(easy-menu-define markdown-mode-menu markdown-mode-map
  "Menu for Markdown mode"
  '("Markdown"
    "---"
    ("Movement"
     ["Jump" markdown-jump]
     ["Follow Link" markdown-follow-thing-at-point]
     ["Next Link" markdown-next-link]
     ["Previous Link" markdown-previous-link]
     "---"
     ["Next Visible Heading" markdown-next-visible-heading]
     ["Previous Visible Heading" markdown-previous-visible-heading]
     ["Forward Same Level" markdown-forward-same-level]
     ["Backward Same Level" markdown-backward-same-level]
     ["Up to Parent Heading" markdown-up-heading]
     "---"
     ["Forward Paragraph" markdown-forward-paragraph]
     ["Backward Paragraph" markdown-backward-paragraph])
    ("Show/Hide"
     ["Cycle Visibility" markdown-cycle (markdown-on-heading-p)]
     ["Cycle Visibility Globally" markdown-shifttab])
    "---"
    ("Headings & Structure"
     ["Automatic Heading" markdown-insert-header-dwim]
     ["Automatic Heading (Setext)" markdown-insert-header-setext-dwim]
     ("Specific Heading (atx)"
      ["First Level Setext" markdown-insert-header-setext-1]
      ["Second Level Setext" markdown-insert-header-setext-2])
     ("Specific Heading (Setext)"
      ["First Level atx" markdown-insert-header-atx-1]
      ["Second Level atx" markdown-insert-header-atx-2]
      ["Third Level atx" markdown-insert-header-atx-3]
      ["Fourth Level atx" markdown-insert-header-atx-4]
      ["Fifth Level atx" markdown-insert-header-atx-5]
      ["Sixth Level atx" markdown-insert-header-atx-6])
     ["Horizontal Rule" markdown-insert-hr]
     "---"
     ["Promote Header" markdown-promote]
     ["Demote Header" markdown-demote]
     ["Promote Subtree" markdown-promote-subtree]
     ["Demote Subtree" markdown-demote-subtree]
     ["Move Subtree Up" markdown-move-subtree-up]
     ["Move Subtree Down" markdown-move-subtree-down])
    ("Region Editing"
     ["Indent Region" markdown-indent-region]
     ["Exdent Region" markdown-exdent-region])
    ("Lists"
     ["Insert List Item" markdown-insert-list-item]
     ["Indent List Item" markdown-demote]
     ["Exdent List Item" markdown-promote]
     ["Move List Item Up" markdown-move-up]
     ["Move List Item Down" markdown-move-down]
     ["Renumber List" markdown-cleanup-list-numbers]
     ["Toggle Task List Item" markdown-toggle-gfm-checkbox])
    ("Links & Images"
     ["Plain URL" markdown-insert-uri]
     ["Inline Link" markdown-insert-inline-link-dwim]
     ["Inline Image" markdown-insert-image]
     ["Reference Link" markdown-insert-reference-link-dwim]
     ["Reference Image" markdown-insert-reference-image]
     ["Footnote" markdown-insert-footnote]
     ["Wiki Link" markdown-insert-wiki-link]
     "---"
     ["Check References" markdown-check-refs]
     ["Toggle Inline Images" markdown-toggle-inline-images
      :style toggle :selected markdown-inline-image-overlays])
    ("Styles"
     ["Bold" markdown-insert-bold]
     ["Italic" markdown-insert-italic]
     ["Code" markdown-insert-code]
     ["Strikethrough" markdown-insert-strike-through]
     ["Keyboard" markdown-insert-kbd]
     "---"
     ["Blockquote" markdown-insert-blockquote]
     ["Preformatted" markdown-insert-pre]
     ["GFM Code Block" markdown-insert-gfm-code-block]
     "---"
     ["Blockquote Region" markdown-blockquote-region]
     ["Preformatted Region" markdown-pre-region])
    "---"
    ("Preview & Export"
     ["Compile" markdown-other-window]
     ["Preview" markdown-preview]
     ["Export" markdown-export]
     ["Export & View" markdown-export-and-preview]
     ["Open" markdown-open]
     ["Live Export" markdown-live-preview-mode
      :style toggle :selected markdown-live-preview-mode]
     ["Kill ring save" markdown-kill-ring-save])
    ("Markup Completion and Cycling"
     ["Complete Markup" markdown-complete]
     ["Promote Element" markdown-promote]
     ["Demote Element" markdown-demote])
    "---"
    ["Kill Element" markdown-kill-thing-at-point]
    "---"
    ("Documentation"
     ["Version" markdown-show-version]
     ["Homepage" markdown-mode-info]
     ["Describe Mode" (describe-function 'markdown-mode)])))

\f
;;; imenu =====================================================================

(defun markdown-imenu-create-nested-index ()
  "Create and return a nested imenu index alist for the current buffer.
See `imenu-create-index-function' and `imenu--index-alist' for details."
  (let* ((root '(nil . nil))
         cur-alist
         (cur-level 0)
         (empty-heading "-")
         (self-heading ".")
         hashes pos level heading)
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward markdown-regex-header (point-max) t)
        (unless (markdown-code-block-at-point)
          (cond
           ((match-string-no-properties 2) ;; level 1 setext
            (setq heading (match-string-no-properties 1))
            (setq pos (match-beginning 1)
                  level 1))
           ((match-string-no-properties 3) ;; level 2 setext
            (setq heading (match-string-no-properties 1))
            (setq pos (match-beginning 1)
                  level 2))
           ((setq hashes (match-string-no-properties 4))
            (setq heading (match-string-no-properties 5)
                  pos (match-beginning 4)
                  level (length hashes))))
          (let ((alist (list (cons heading pos))))
            (cond
             ((= cur-level level)       ; new sibling
              (setcdr cur-alist alist)
              (setq cur-alist alist))
             ((< cur-level level)       ; first child
              (dotimes (_ (- level cur-level 1))
                (setq alist (list (cons empty-heading alist))))
              (if cur-alist
                  (let* ((parent (car cur-alist))
                         (self-pos (cdr parent)))
                    (setcdr parent (cons (cons self-heading self-pos) alist)))
                (setcdr root alist))    ; primogenitor
              (setq cur-alist alist)
              (setq cur-level level))
             (t                         ; new sibling of an ancestor
              (let ((sibling-alist (last (cdr root))))
                (dotimes (_ (1- level))
                  (setq sibling-alist (last (cdar sibling-alist))))
                (setcdr sibling-alist alist)
                (setq cur-alist alist))
              (setq cur-level level))))))
      (cdr root))))

(defun markdown-imenu-create-flat-index ()
  "Create and return a flat imenu index alist for the current buffer.
See `imenu-create-index-function' and `imenu--index-alist' for details."
  (let* ((empty-heading "-") index heading pos)
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward markdown-regex-header (point-max) t)
        (when (and (not (markdown-code-block-at-point))
                   (not (markdown-text-property-at-point 'markdown-yaml-metadata-begin)))
          (cond
           ((setq heading (match-string-no-properties 1))
            (setq pos (match-beginning 1)))
           ((setq heading (match-string-no-properties 5))
            (setq pos (match-beginning 4))))
          (or (> (length heading) 0)
              (setq heading empty-heading))
          (setq index (append index (list (cons heading pos))))))
      index)))

\f
;;; References ================================================================

(defun markdown-reference-goto-definition ()
  "Jump to the definition of the reference at point or create it."
  (interactive)
  (when (thing-at-point-looking-at markdown-regex-link-reference)
    (let* ((text (match-string-no-properties 3))
           (reference (match-string-no-properties 6))
           (target (downcase (if (string= reference "") text reference)))
           (loc (cadr (markdown-reference-definition target))))
      (if loc
          (goto-char loc)
        (goto-char (match-beginning 0))
        (markdown-insert-reference-definition target)))))

(defun markdown-reference-find-links (reference)
  "Return a list of all links for REFERENCE.
REFERENCE should not include the surrounding square brackets.
Elements of the list have the form (text start line), where
text is the link text, start is the location at the beginning of
the link, and line is the line number on which the link appears."
  (let* ((ref-quote (regexp-quote reference))
         (regexp (format "!?\\(?:\\[\\(%s\\)\\][ ]?\\[\\]\\|\\[\\([^]]+?\\)\\][ ]?\\[%s\\]\\)"
                         ref-quote ref-quote))
         links)
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward regexp nil t)
        (let* ((text (or (match-string-no-properties 1)
                         (match-string-no-properties 2)))
               (start (match-beginning 0))
               (line (markdown-line-number-at-pos)))
          (cl-pushnew (list text start line) links :test #'equal))))
    links))

(defun markdown-get-undefined-refs ()
  "Return a list of undefined Markdown references.
Result is an alist of pairs (reference . occurrences), where
occurrences is itself another alist of pairs (label . line-number).
For example, an alist corresponding to [Nice editor][Emacs] at line 12,
\[GNU Emacs][Emacs] at line 45 and [manual][elisp] at line 127 is
\((\"emacs\" (\"Nice editor\" . 12) (\"GNU Emacs\" . 45)) (\"elisp\" (\"manual\" . 127)))."
  (let ((missing))
    (save-excursion
      (goto-char (point-min))
      (while
          (re-search-forward markdown-regex-link-reference nil t)
        (let* ((text (match-string-no-properties 3))
               (reference (match-string-no-properties 6))
               (target (downcase (if (string= reference "") text reference))))
          (unless (markdown-reference-definition target)
            (let ((entry (assoc target missing)))
              (if (not entry)
                  (cl-pushnew
                   (cons target (list (cons text (markdown-line-number-at-pos))))
                   missing :test #'equal)
                (setcdr entry
                        (append (cdr entry) (list (cons text (markdown-line-number-at-pos))))))))))
      (reverse missing))))

(defconst markdown-reference-check-buffer
  "*Undefined references for %buffer%*"
  "Pattern for name of buffer for listing undefined references.
The string %buffer% will be replaced by the corresponding
`markdown-mode' buffer name.")

(defun markdown-reference-check-buffer (&optional buffer-name)
  "Name and return buffer for reference checking.
BUFFER-NAME is the name of the main buffer being visited."
  (or buffer-name (setq buffer-name (buffer-name)))
  (let ((refbuf (get-buffer-create (markdown-replace-regexp-in-string
                                    "%buffer%" buffer-name
                                    markdown-reference-check-buffer))))
    (with-current-buffer refbuf
      (when view-mode
        (View-exit-and-edit))
      (use-local-map button-buffer-map)
      (erase-buffer))
    refbuf))

(defconst markdown-reference-links-buffer
  "*Reference links for %buffer%*"
  "Pattern for name of buffer for listing references.
The string %buffer% will be replaced by the corresponding buffer name.")

(defun markdown-reference-links-buffer (&optional buffer-name)
  "Name, setup, and return a buffer for listing links.
BUFFER-NAME is the name of the main buffer being visited."
  (or buffer-name (setq buffer-name (buffer-name)))
  (let ((linkbuf (get-buffer-create (markdown-replace-regexp-in-string
                                     "%buffer%" buffer-name
                                     markdown-reference-links-buffer))))
    (with-current-buffer linkbuf
      (when view-mode
        (View-exit-and-edit))
      (use-local-map button-buffer-map)
      (erase-buffer))
    linkbuf))

(when (markdown-use-buttons-p)
  ;; Add an empty Markdown reference definition to buffer
  ;; specified in the 'target-buffer property.  The reference name is
  ;; the button's label.
  (define-button-type 'markdown-undefined-reference-button
    'help-echo "mouse-1, RET: create definition for undefined reference"
    'follow-link t
    'face 'bold
    'action (lambda (b)
              (let ((buffer (button-get b 'target-buffer))
                    (line (button-get b 'target-line))
                    (label (button-label b)))
                (switch-to-buffer-other-window buffer)
                (goto-char (point-min))
                (forward-line line)
                (markdown-insert-reference-definition label)
                (markdown-check-refs t))))

  ;; Jump to line in buffer specified by 'target-buffer property.
  ;; Line number is button's 'line property.
  (define-button-type 'markdown-goto-line-button
    'help-echo "mouse-1, RET: go to line"
    'follow-link t
    'face 'italic
    'action (lambda (b)
              (message (button-get b 'buffer))
              (switch-to-buffer-other-window (button-get b 'target-buffer))
              ;; use call-interactively to silence compiler
              (let ((current-prefix-arg (button-get b 'target-line)))
                (call-interactively 'goto-line))))

  ;; Jumps to a particular link at location given by 'target-char
  ;; property in buffer given by 'target-buffer property.
  (define-button-type 'markdown-link-button
    'help-echo "mouse-1, RET: jump to location of link"
    'follow-link t
    'face 'bold
    'action (lambda (b)
              (let ((target (button-get b 'target-buffer))
                    (loc (button-get b 'target-char)))
                (kill-buffer-and-window)
                (switch-to-buffer target)
                (goto-char loc)))))

(defun markdown-insert-undefined-reference-button (reference oldbuf)
  "Insert a button for creating REFERENCE in buffer OLDBUF.
REFERENCE should be a list of the form (reference . occurrences),
as by `markdown-get-undefined-refs'."
  (let ((label (car reference)))
    (if (markdown-use-buttons-p)
        ;; Create a reference button in Emacs 22
        (insert-button label
                       :type 'markdown-undefined-reference-button
                       'target-buffer oldbuf
                       'target-line (cdr (car (cdr reference))))
      ;; Insert reference as text in Emacs < 22
      (insert label))
    (insert " (")
    (dolist (occurrence (cdr reference))
      (let ((line (cdr occurrence)))
        (if (markdown-use-buttons-p)
            ;; Create a line number button in Emacs 22
            (insert-button (number-to-string line)
                           :type 'markdown-goto-line-button
                           'target-buffer oldbuf
                           'target-line line)
          ;; Insert line number as text in Emacs < 22
          (insert (number-to-string line)))
        (insert " ")))
    (delete-char -1)
    (insert ")")
    (newline)))

(defun markdown-insert-link-button (link oldbuf)
  "Insert a button for jumping to LINK in buffer OLDBUF.
LINK should be a list of the form (text char line) containing
the link text, location, and line number."
  (let ((label (cl-first link))
        (char (cl-second link))
        (line (cl-third link)))
    (if (markdown-use-buttons-p)
        ;; Create a reference button in Emacs 22
        (insert-button label
                       :type 'markdown-link-button
                       'target-buffer oldbuf
                       'target-char char)
      ;; Insert reference as text in Emacs < 22
      (insert label))
    (insert (format " (line %d)\n" line))))

(defun markdown-reference-goto-link (&optional reference)
  "Jump to the location of the first use of REFERENCE."
  (interactive)
  (unless reference
    (if (thing-at-point-looking-at markdown-regex-reference-definition)
        (setq reference (match-string-no-properties 2))
      (error "No reference definition at point")))
  (let ((links (markdown-reference-find-links reference)))
    (cond ((= (length links) 1)
           (goto-char (cadr (car links))))
          ((> (length links) 1)
           (let ((oldbuf (current-buffer))
                 (linkbuf (markdown-reference-links-buffer)))
             (with-current-buffer linkbuf
               (insert "Links using reference " reference ":\n\n")
               (dolist (link (reverse links))
                 (markdown-insert-link-button link oldbuf)))
             (view-buffer-other-window linkbuf)
             (goto-char (point-min))
             (forward-line 2)))
          (t
           (error "No links for reference %s" reference)))))

(defun markdown-check-refs (&optional silent)
  "Show all undefined Markdown references in current `markdown-mode' buffer.
If SILENT is non-nil, do not message anything when no undefined
references found.
Links which have empty reference definitions are considered to be
defined."
  (interactive "P")
  (when (not (eq major-mode 'markdown-mode))
    (error "Not available in current mode"))
  (let ((oldbuf (current-buffer))
        (refs (markdown-get-undefined-refs))
        (refbuf (markdown-reference-check-buffer)))
    (if (null refs)
        (progn
          (when (not silent)
            (message "No undefined references found"))
          (kill-buffer refbuf))
      (with-current-buffer refbuf
        (insert "The following references are undefined:\n\n")
        (dolist (ref refs)
          (markdown-insert-undefined-reference-button ref oldbuf))
        (view-buffer-other-window refbuf)
        (goto-char (point-min))
        (forward-line 2)))))

\f
;;; Lists =====================================================================

(defun markdown-insert-list-item (&optional arg)
  "Insert a new list item.
If the point is inside unordered list, insert a bullet mark.  If
the point is inside ordered list, insert the next number followed
by a period.  Use the previous list item to determine the amount
of whitespace to place before and after list markers.

With a \\[universal-argument] prefix (i.e., when ARG is (4)),
decrease the indentation by one level.

With two \\[universal-argument] prefixes (i.e., when ARG is (16)),
increase the indentation by one level."
  (interactive "p")
  (let (bounds cur-indent marker indent new-indent new-loc)
    (save-match-data
      ;; Look for a list item on current or previous non-blank line
      (save-excursion
        (while (and (not (setq bounds (markdown-cur-list-item-bounds)))
                    (not (bobp))
                    (markdown-cur-line-blank-p))
          (forward-line -1)))
      (when bounds
        (cond ((save-excursion
                 (skip-chars-backward " \t")
                 (looking-at-p markdown-regex-list))
               (beginning-of-line)
               (insert "\n")
               (forward-line -1))
              ((not (markdown-cur-line-blank-p))
               (newline)))
        (setq new-loc (point)))
      ;; Look ahead for a list item on next non-blank line
      (unless bounds
        (save-excursion
          (while (and (null bounds)
                      (not (eobp))
                      (markdown-cur-line-blank-p))
            (forward-line)
            (setq bounds (markdown-cur-list-item-bounds))))
        (when bounds
          (setq new-loc (point))
          (unless (markdown-cur-line-blank-p)
            (newline))))
      (if (not bounds)
          ;; When not in a list, start a new unordered one
          (progn
            (unless (markdown-cur-line-blank-p)
              (insert "\n"))
            (insert markdown-unordered-list-item-prefix))
        ;; Compute indentation and marker for new list item
        (setq cur-indent (nth 2 bounds))
        (setq marker (nth 4 bounds))
        (cond
         ;; Dedent: decrement indentation, find previous marker.
         ((= arg 4)
          (setq indent (max (- cur-indent 4) 0))
          (let ((prev-bounds
                 (save-excursion
                   (when (markdown-prev-list-item (- (nth 3 bounds) 1))
                     (markdown-cur-list-item-bounds)))))
            (when prev-bounds
              (setq marker (nth 4 prev-bounds)))))
         ;; Indent: increment indentation by 4, use same marker.
         ((= arg 16) (setq indent (+ cur-indent 4)))
         ;; Same level: keep current indentation and marker.
         (t (setq indent cur-indent)))
        (setq new-indent (make-string indent 32))
        (goto-char new-loc)
        (cond
         ;; Ordered list
         ((string-match-p "[0-9]" marker)
          (if (= arg 16) ;; starting a new column indented one more level
              (insert (concat new-indent "1. "))
            ;; Don't use previous match-data
            (set-match-data nil)
            ;; travel up to the last item and pick the correct number.  If
            ;; the argument was nil, "new-indent = cur-indent" is the same,
            ;; so we don't need special treatment. Neat.
            (save-excursion
              (while (and (not (looking-at (concat new-indent "\\([0-9]+\\)\\(\\.[ \t]*\\)")))
                          (>= (forward-line -1) 0))))
            (let* ((old-prefix (match-string 1))
                   (old-spacing (match-string 2))
                   (new-prefix (if old-prefix
                                   (int-to-string (1+ (string-to-number old-prefix)))
                                 "1"))
                   (space-adjust (- (length old-prefix) (length new-prefix)))
                   (new-spacing (if (and (match-string 2)
                                         (not (string-match-p "\t" old-spacing))
                                         (< space-adjust 0)
                                         (> space-adjust (- 1 (length (match-string 2)))))
                                    (substring (match-string 2) 0 space-adjust)
                                  (or old-spacing ". "))))
              (insert (concat new-indent new-prefix new-spacing)))))
         ;; Unordered list, or ordered list with hash mark
         ((string-match-p "[\\*\\+-]\\|#\\." marker)
          (insert new-indent marker)))))))

(defun markdown-move-list-item-up ()
  "Move the current list item up in the list when possible."
  (interactive)
  (let (cur prev old)
    (when (setq cur (markdown-cur-list-item-bounds))
      (setq old (point))
      (goto-char (nth 0 cur))
      (if (markdown-prev-list-item (nth 3 cur))
          (progn
            (setq prev (markdown-cur-list-item-bounds))
            (condition-case nil
                (progn
                  (transpose-regions (nth 0 prev) (nth 1 prev)
                                     (nth 0 cur) (nth 1 cur) t)
                  (goto-char (+ (nth 0 prev) (- old (nth 0 cur)))))
              ;; Catch error in case regions overlap.
              (error (goto-char old))))
        (goto-char old)))))

(defun markdown-move-list-item-down ()
  "Move the current list item down in the list when possible."
  (interactive)
  (let (cur next old)
    (when (setq cur (markdown-cur-list-item-bounds))
      (setq old (point))
      (if (markdown-next-list-item (nth 3 cur))
          (progn
            (setq next (markdown-cur-list-item-bounds))
            (condition-case nil
                (progn
                  (transpose-regions (nth 0 cur) (nth 1 cur)
                                     (nth 0 next) (nth 1 next) nil)
                  (goto-char (+ old (- (nth 1 next) (nth 1 cur)))))
              ;; Catch error in case regions overlap.
              (error (goto-char old))))
        (goto-char old)))))

(defun markdown-demote-list-item (&optional bounds)
  "Indent (or demote) the current list item.
Optionally, BOUNDS of the current list item may be provided if available."
  (interactive)
  (when (or bounds (setq bounds (markdown-cur-list-item-bounds)))
    (save-excursion
      (let ((end-marker (set-marker (make-marker) (nth 1 bounds))))
        (goto-char (nth 0 bounds))
        (while (< (point) end-marker)
          (unless (markdown-cur-line-blank-p)
            (insert (make-string markdown-list-indent-width ? )))
          (forward-line))))))

(defun markdown-promote-list-item (&optional bounds)
  "Unindent (or promote) the current list item.
Optionally, BOUNDS of the current list item may be provided if available."
  (interactive)
  (when (or bounds (setq bounds (markdown-cur-list-item-bounds)))
    (save-excursion
      (save-match-data
        (let ((end-marker (set-marker (make-marker) (nth 1 bounds)))
              num regexp)
          (goto-char (nth 0 bounds))
          (when (looking-at (format "^[ ]\\{1,%d\\}"
                                    markdown-list-indent-width))
            (setq num (- (match-end 0) (match-beginning 0)))
            (setq regexp (format "^[ ]\\{1,%d\\}" num))
            (while (and (< (point) end-marker)
                        (re-search-forward regexp end-marker t))
              (replace-match "" nil nil)
              (forward-line))))))))

(defun markdown-cleanup-list-numbers-level (&optional pfx)
  "Update the numbering for level PFX (as a string of spaces).

Assume that the previously found match was for a numbered item in
a list."
  (let ((cpfx pfx)
        (idx 0)
        (continue t)
        (step t)
        (sep nil))
    (while (and continue (not (eobp)))
      (setq step t)
      (cond
       ((looking-at "^\\([\s-]*\\)[0-9]+\\. ")
        (setq cpfx (match-string-no-properties 1))
        (cond
         ((string= cpfx pfx)
          (save-excursion
            (replace-match
             (concat pfx (number-to-string (setq idx (1+ idx))) ". ")))
          (setq sep nil))
         ;; indented a level
         ((string< pfx cpfx)
          (setq sep (markdown-cleanup-list-numbers-level cpfx))
          (setq step nil))
         ;; exit the loop
         (t
          (setq step nil)
          (setq continue nil))))

       ((looking-at "^\\([\s-]*\\)[^ \t\n\r].*$")
        (setq cpfx (match-string-no-properties 1))
        (cond
         ;; reset if separated before
         ((string= cpfx pfx) (when sep (setq idx 0)))
         ((string< cpfx pfx)
          (setq step nil)
          (setq continue nil))))
       (t (setq sep t)))

      (when step
        (beginning-of-line)
        (setq continue (= (forward-line) 0))))
    sep))

(defun markdown-cleanup-list-numbers ()
  "Update the numbering of ordered lists."
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (markdown-cleanup-list-numbers-level "")))

\f
;;; Movement ==================================================================

(defun markdown-beginning-of-defun (&optional arg)
  "`beginning-of-defun-function' for Markdown.
Move backward to the beginning of the current or previous section.
When ARG is non-nil, repeat that many times.  When ARG is negative,
move forward to the ARG-th following section."
  (interactive "P")
  (or arg (setq arg 1))
  (forward-char 1)
  (or (re-search-backward markdown-regex-header nil t arg)
      (goto-char (point-min))))

(defun markdown-end-of-defun (&optional arg)
  "`end-of-defun-function' for Markdown.
Move forward to the end of the current or following section.
When ARG is non-nil, repeat that many times.  When ARG is negative,
move back to the ARG-th preceding section."
  (interactive "P")
  (or arg (setq arg 1))
  (when (looking-at markdown-regex-header)
    (goto-char (match-beginning 0))
    (forward-char 1))
  (if (re-search-forward markdown-regex-header nil t arg)
      (goto-char (match-beginning 0))
    (goto-char (point-max)))
  (skip-syntax-backward "-"))

(defun markdown-beginning-of-block ()
  "Move the point to the start of the previous text block."
  (interactive)
  (if (re-search-backward markdown-regex-block-separator nil t)
      (goto-char (or (match-end 2) (match-end 0)))
    (goto-char (point-min))))

(defun markdown-end-of-block ()
  "Move the point to the start of the next text block."
  (interactive)
  (beginning-of-line)
  (skip-syntax-forward "-")
  (when (= (point) (point-min))
    (forward-char))
  (if (re-search-forward markdown-regex-block-separator nil t)
      (goto-char (or (match-end 2) (match-end 0)))
    (goto-char (point-max)))
  (skip-syntax-backward "-")
  (forward-line))

(defun markdown-forward-paragraph (arg)
  "Move forward one or more paragraphs or by one block.
When ARG is nil or a numeric prefix, call `forward-paragraph'
with ARG.  When called with \\[universal-argument], call
`markdown-end-of-block' instead."
  (interactive "P")
  (or arg (setq arg 1))
  (cond ((integerp arg)
         (forward-paragraph arg))
        ((equal arg '(4))
         (markdown-end-of-block))))

(defun markdown-backward-paragraph (arg)
  "Move backward one or more paragraphs or by one block.
When ARG is nil or a numeric prefix, call `backward-paragraph'
with ARG.  When called with \\[universal-argument], call
`markdown-beginning-of-block' instead."
  (interactive "P")
  (or arg (setq arg 1))
  (cond ((integerp arg)
         (backward-paragraph arg))
        ((equal arg '(4))
         (markdown-beginning-of-block))))

(defun markdown-end-of-block-element ()
  "Move the point to the start of the next block unit.
Stops at blank lines, list items, headers, and horizontal rules."
  (interactive)
  (forward-line)
  (while (and (or (not (markdown-prev-line-blank-p))
                  (markdown-cur-line-blank-p))
              (not (or (looking-at-p markdown-regex-list)
                       (looking-at-p markdown-regex-header)
                       (looking-at-p markdown-regex-hr)))
              (not (eobp)))
    (forward-line)))

(defun markdown-next-link ()
  "Jump to next inline, reference, or wiki link.
If successful, return point.  Otherwise, return nil.
See `markdown-wiki-link-p' and `markdown-previous-wiki-link'."
  (interactive)
  (let ((opoint (point)))
    (when (or (markdown-link-p) (markdown-wiki-link-p))
      ;; At a link already, move past it.
      (goto-char (+ (match-end 0) 1)))
    ;; Search for the next wiki link and move to the beginning.
    (while (and (re-search-forward (markdown-make-regex-link-generic) nil t)
                (markdown-code-block-at-point)
                (< (point) (point-max))))
    (if (and (not (eq (point) opoint))
             (or (markdown-link-p) (markdown-wiki-link-p)))
        ;; Group 1 will move past non-escape character in wiki link regexp.
        ;; Go to beginning of group zero for all other link types.
        (goto-char (or (match-beginning 1) (match-beginning 0)))
      (goto-char opoint)
      nil)))

(defun markdown-previous-link ()
  "Jump to previous wiki link.
If successful, return point.  Otherwise, return nil.
See `markdown-wiki-link-p' and `markdown-next-wiki-link'."
  (interactive)
  (let ((opoint (point)))
    (while (and (re-search-backward (markdown-make-regex-link-generic) nil t)
                (markdown-code-block-at-point)
                (> (point) (point-min))))
    (if (and (not (eq (point) opoint))
             (or (markdown-link-p) (markdown-wiki-link-p)))
        (goto-char (or (match-beginning 1) (match-beginning 0)))
      (goto-char opoint)
      nil)))

(defun markdown-next-heading ()
  "Move to the next heading line of any level.
With argument, repeats or can move backward if negative."
  (let ((pos (outline-next-heading)))
    (while (markdown-code-block-at-point)
      (setq pos (outline-next-heading)))
    pos))

(defun markdown-previous-heading ()
  "Move to the previous heading line of any level.
With argument, repeats or can move backward if negative."
  (let ((pos (outline-previous-heading)))
    (while (markdown-code-block-at-point)
      (setq pos (outline-previous-heading)))
    pos))

\f
;;; Outline ===================================================================

(defun markdown-move-heading-common (move-fn &optional arg)
  "Wrapper for `outline-mode' functions to skip false positives.
MOVE-FN is a function and ARG is its argument. For example,
headings inside preformatted code blocks may match
`outline-regexp' but should not be considered as headings."
  (funcall move-fn arg)
  (let ((prev -1))
    (while (and (/= prev (point)) (markdown-code-block-at-point))
      (setq prev (point))
      (funcall move-fn arg))))

(defun markdown-next-visible-heading (arg)
  "Move to the next visible heading line of any level.
With argument, repeats or can move backward if negative. ARG is
passed to `outline-next-visible-heading'."
  (interactive "p")
  (markdown-move-heading-common 'outline-next-visible-heading arg))

(defun markdown-previous-visible-heading (arg)
  "Move to the previous visible heading line of any level.
With argument, repeats or can move backward if negative. ARG is
passed to `outline-previous-visible-heading'."
  (interactive "p")
  (markdown-move-heading-common 'outline-previous-visible-heading arg))

(defun markdown-forward-same-level (arg)
  "Move forward to the ARG'th heading at same level as this one.
Stop at the first and last headings of a superior heading."
  (interactive "p")
  (markdown-move-heading-common 'outline-forward-same-level arg))

(defun markdown-back-to-heading-over-code-block (&optional invisible-ok)
  (beginning-of-line)
  (or (and (outline-on-heading-p invisible-ok)
           (not (markdown-code-block-at-point)))
      (let ((header-re (concat "^\\(?:" outline-regexp "\\)"))
            found)
        (save-excursion
          (while (not found)
            (let (finish)
              (while (and (not finish) (re-search-backward header-re nil t))
                (when (and (or invisible-ok (not (outline-invisible-p)))
                           (not (markdown-code-block-at-point)))
                  (setq finish t)))
              (if (not finish)
                  (error "Before first heading")
                (setq found (point))))))
        (goto-char found)
        found)))

(defun markdown-backward-same-level (arg)
  "Move backward to the ARG'th heading at same level as this one.
Stop at the first and last headings of a superior heading."
  (interactive "p")
  (markdown-back-to-heading-over-code-block)
  (while (> arg 0)
    (let ((point-to-move-to (save-excursion
                              (outline-get-last-sibling))))
      (if point-to-move-to
          (progn
            (goto-char point-to-move-to)
            (setq arg (1- arg)))
        (error "No previous same-level heading")))))

(defun markdown-up-heading (arg)
  "Move to the visible heading line of which the present line is a subheading.
With argument, move up ARG levels."
  (interactive "p")
  (markdown-move-heading-common 'outline-up-heading arg))

(defun markdown-back-to-heading (&optional invisible-ok)
  "Move to previous heading line, or beg of this line if it's a heading.
Only visible heading lines are considered, unless INVISIBLE-OK is non-nil."
  (markdown-move-heading-common 'outline-back-to-heading invisible-ok))

(defalias 'markdown-end-of-heading 'outline-end-of-heading)

(defun markdown-on-heading-p ()
  "Return t if point is on a (visible) heading line."
  (get-text-property (point) 'markdown-heading))

(defun markdown-end-of-subtree (&optional invisible-OK)
  "Move to the end of the current subtree.
Only visible heading lines are considered, unless INVISIBLE-OK is
non-nil.
Derived from `org-end-of-subtree'."
  (markdown-back-to-heading invisible-OK)
  (let ((first t)
        (level (funcall outline-level)))
    (while (and (not (eobp))
                (or first (> (funcall outline-level) level)))
      (setq first nil)
      (markdown-next-heading))
    (if (memq (preceding-char) '(?\n ?\^M))
        (progn
          ;; Go to end of line before heading
          (forward-char -1)
          (if (memq (preceding-char) '(?\n ?\^M))
              ;; leave blank line before heading
              (forward-char -1)))))
  (point))

(defun markdown-outline-fix-visibility ()
  "Hide any false positive headings that should not be shown.
For example, headings inside preformatted code blocks may match
`outline-regexp' but should not be shown as headings when cycling.
Also, the ending --- line in metadata blocks appears to be a
setext header, but should not be folded."
  (save-excursion
    (goto-char (point-min))
    ;; Unhide any false positives in metadata blocks
    (when (markdown-text-property-at-point 'markdown-yaml-metadata-begin)
      (let ((body (progn (forward-line)
                         (markdown-text-property-at-point
                          'markdown-yaml-metadata-section))))
        (when body
          (let ((end (progn (goto-char (cl-second body))
                            (markdown-text-property-at-point
                             'markdown-yaml-metadata-end))))
            (outline-flag-region (point-min) (1+ (cl-second end)) nil)))))
    ;; Hide any false positives in code blocks
    (unless (outline-on-heading-p)
      (outline-next-visible-heading 1))
    (while (< (point) (point-max))
      (when (markdown-code-block-at-point)
        (outline-flag-region (1- (point-at-bol)) (point-at-eol) t))
      (outline-next-visible-heading 1))))

(defvar markdown-cycle-global-status 1)
(defvar markdown-cycle-subtree-status nil)

(defun markdown-next-preface ()
  (let (finish)
    (while (and (not finish) (re-search-forward (concat "\n\\(?:" outline-regexp "\\)")
                                                nil 'move))
      (unless (markdown-code-block-at-point)
        (goto-char (match-beginning 0))
        (setq finish t))))
  (when (and (bolp) (or outline-blank-line (eobp)) (not (bobp)))
    (forward-char -1)))

(defun markdown-show-entry ()
  (save-excursion
    (outline-back-to-heading t)
    (outline-flag-region (1- (point))
                         (progn
                           (markdown-next-preface)
                           (if (= 1 (- (point-max) (point)))
                               (point-max)
                             (point)))
                         nil)))

(defun markdown-cycle (&optional arg)
  "Visibility cycling for Markdown mode.
If ARG is t, perform global visibility cycling.  If the point is
at an atx-style header, cycle visibility of the corresponding
subtree.  Otherwise, insert a tab using `indent-relative'.
Derived from `org-cycle'."
  (interactive "P")
  (cond
   ((eq arg t) ;; Global cycling
    (cond
     ((and (eq last-command this-command)
           (eq markdown-cycle-global-status 2))
      ;; Move from overview to contents
      (markdown-hide-sublevels 1)
      (message "CONTENTS")
      (setq markdown-cycle-global-status 3)
      (markdown-outline-fix-visibility))

     ((and (eq last-command this-command)
           (eq markdown-cycle-global-status 3))
      ;; Move from contents to all
      (markdown-show-all)
      (message "SHOW ALL")
      (setq markdown-cycle-global-status 1))

     (t
      ;; Defaults to overview
      (markdown-hide-body)
      (message "OVERVIEW")
      (setq markdown-cycle-global-status 2)
      (markdown-outline-fix-visibility))))

   ((save-excursion (beginning-of-line 1) (markdown-on-heading-p))
    ;; At a heading: rotate between three different views
    (markdown-back-to-heading)
    (let ((goal-column 0) eoh eol eos)
      ;; Determine boundaries
      (save-excursion
        (markdown-back-to-heading)
        (save-excursion
          (beginning-of-line 2)
          (while (and (not (eobp)) ;; this is like `next-line'
                      (get-char-property (1- (point)) 'invisible))
            (beginning-of-line 2)) (setq eol (point)))
        (markdown-end-of-heading)   (setq eoh (point))
        (markdown-end-of-subtree t)
        (skip-chars-forward " \t\n")
        (beginning-of-line 1) ; in case this is an item
        (setq eos (1- (point))))
      ;; Find out what to do next and set `this-command'
      (cond
       ((= eos eoh)
        ;; Nothing is hidden behind this heading
        (message "EMPTY ENTRY")
        (setq markdown-cycle-subtree-status nil))
       ((>= eol eos)
        ;; Entire subtree is hidden in one line: open it
        (markdown-show-entry)
        (markdown-show-children)
        (message "CHILDREN")
        (setq markdown-cycle-subtree-status 'children))
       ((and (eq last-command this-command)
             (eq markdown-cycle-subtree-status 'children))
        ;; We just showed the children, now show everything.
        (markdown-show-subtree)
        (message "SUBTREE")
        (setq markdown-cycle-subtree-status 'subtree))
       (t
        ;; Default action: hide the subtree.
        (markdown-hide-subtree)
        (message "FOLDED")
        (setq markdown-cycle-subtree-status 'folded)))))

   (t
    (indent-for-tab-command))))

(defun markdown-shifttab ()
  "Global visibility cycling.
Calls `markdown-cycle' with argument t."
  (interactive)
  (markdown-cycle t))

(defun markdown-outline-level ()
  "Return the depth to which a statement is nested in the outline."
  (cond
   ((markdown-code-block-at-point) 7)
   ((match-end 2) 1)
   ((match-end 3) 2)
   ((- (match-end 4) (match-beginning 4)))))

(defun markdown-promote-subtree (&optional arg)
  "Promote the current subtree of ATX headings.
Note that Markdown does not support heading levels higher than
six and therefore level-six headings will not be promoted
further. If ARG is non-nil promote the heading, otherwise
demote."
  (interactive "*P")
  (save-excursion
    (when (and (or (thing-at-point-looking-at markdown-regex-header-atx)
                   (re-search-backward markdown-regex-header-atx nil t))
               (not (markdown-code-block-at-point)))
      (let ((level (length (match-string 1)))
            (promote-or-demote (if arg 1 -1))
            (remove 't))
        (markdown-cycle-atx promote-or-demote remove)
        (catch 'end-of-subtree
          (while (markdown-next-heading)
            ;; Exit if this not a higher level heading; promote otherwise.
            (if (and (looking-at markdown-regex-header-atx)
                     (<= (length (match-string-no-properties 1)) level))
                (throw 'end-of-subtree nil)
              (markdown-cycle-atx promote-or-demote remove))))))))

(defun markdown-demote-subtree ()
  "Demote the current subtree of ATX headings."
  (interactive)
  (markdown-promote-subtree t))

(defun markdown-move-subtree-up ()
  "Move the current subtree of ATX headings up."
  (interactive)
  (outline-move-subtree-up 1))

(defun markdown-move-subtree-down ()
  "Move the current subtree of ATX headings down."
  (interactive)
  (outline-move-subtree-down 1))

\f
;;; Generic Structure Editing, Completion, and Cycling Commands ===============

(defun markdown-move-up ()
  "Move list item up.
Calls `markdown-move-list-item-up'."
  (interactive)
  (markdown-move-list-item-up))

(defun markdown-move-down ()
  "Move list item down.
Calls `markdown-move-list-item-down'."
  (interactive)
  (markdown-move-list-item-down))

(defun markdown-promote ()
  "Either promote header or list item at point or cycle markup.
See `markdown-cycle-atx', `markdown-cycle-setext', and
`markdown-promote-list-item'."
  (interactive)
  (let (bounds)
    (cond
     ;; Promote atx header
     ((thing-at-point-looking-at markdown-regex-header-atx)
      (markdown-cycle-atx -1))
     ;; Promote setext header
     ((thing-at-point-looking-at markdown-regex-header-setext)
      (markdown-cycle-setext -1))
     ;; Promote horizonal rule
     ((thing-at-point-looking-at markdown-regex-hr)
      (markdown-cycle-hr -1))
     ;; Promote list item
     ((setq bounds (markdown-cur-list-item-bounds))
      (markdown-promote-list-item bounds))
     ;; Promote bold
     ((thing-at-point-looking-at markdown-regex-bold)
      (markdown-cycle-bold))
     ;; Promote italic
     ((thing-at-point-looking-at markdown-regex-italic)
      (markdown-cycle-italic))
     (t
      (error "Nothing to promote at point")))))

(defun markdown-demote ()
  "Either demote header or list item at point or cycle or remove markup.
See `markdown-cycle-atx', `markdown-cycle-setext', and
`markdown-demote-list-item'."
  (interactive)
  (let (bounds)
    (cond
     ;; Demote atx header
     ((thing-at-point-looking-at markdown-regex-header-atx)
      (markdown-cycle-atx 1))
     ;; Demote setext header
     ((thing-at-point-looking-at markdown-regex-header-setext)
      (markdown-cycle-setext 1))
     ;; Demote horizonal rule
     ((thing-at-point-looking-at markdown-regex-hr)
      (markdown-cycle-hr 1))
     ;; Demote list item
     ((setq bounds (markdown-cur-list-item-bounds))
      (markdown-demote-list-item bounds))
     ;; Demote bold
     ((thing-at-point-looking-at markdown-regex-bold)
      (markdown-cycle-bold))
     ;; Demote italic
     ((thing-at-point-looking-at markdown-regex-italic)
      (markdown-cycle-italic))
     (t
      (error "Nothing to demote at point")))))

\f
;;; Commands ==================================================================

(defun markdown (&optional output-buffer-name)
  "Run `markdown-command' on buffer, sending output to OUTPUT-BUFFER-NAME.
The output buffer name defaults to `markdown-output-buffer-name'.
Return the name of the output buffer used."
  (interactive)
  (save-window-excursion
    (let ((begin-region)
          (end-region))
      (if (markdown-use-region-p)
          (setq begin-region (region-beginning)
                end-region (region-end))
        (setq begin-region (point-min)
              end-region (point-max)))

      (unless output-buffer-name
        (setq output-buffer-name markdown-output-buffer-name))
      (cond
       ;; Handle case when `markdown-command' does not read from stdin
       (markdown-command-needs-filename
        (if (not buffer-file-name)
            (error "Must be visiting a file")
          (shell-command (concat markdown-command " "
                                 (shell-quote-argument buffer-file-name))
                         output-buffer-name)))
       ;; Pass region to `markdown-command' via stdin
       (t
        (let ((buf (get-buffer-create output-buffer-name)))
          (with-current-buffer buf
            (setq buffer-read-only nil)
            (erase-buffer))
          (call-process-region begin-region end-region
                               shell-file-name nil buf nil
                               shell-command-switch markdown-command)))))
    output-buffer-name))

(defun markdown-standalone (&optional output-buffer-name)
  "Special function to provide standalone HTML output.
Insert the output in the buffer named OUTPUT-BUFFER-NAME."
  (interactive)
  (setq output-buffer-name (markdown output-buffer-name))
  (with-current-buffer output-buffer-name
    (set-buffer output-buffer-name)
    (unless (markdown-output-standalone-p)
      (markdown-add-xhtml-header-and-footer output-buffer-name))
    (goto-char (point-min))
    (html-mode))
  output-buffer-name)

(defun markdown-other-window (&optional output-buffer-name)
  "Run `markdown-command' on current buffer and display in other window.
When OUTPUT-BUFFER-NAME is given, insert the output in the buffer with
that name."
  (interactive)
  (markdown-display-buffer-other-window
   (markdown-standalone output-buffer-name)))

(defun markdown-output-standalone-p ()
  "Determine whether `markdown-command' output is standalone XHTML.
Standalone XHTML output is identified by an occurrence of
`markdown-xhtml-standalone-regexp' in the first five lines of output."
  (save-excursion
    (goto-char (point-min))
    (re-search-forward
     markdown-xhtml-standalone-regexp
     (save-excursion (goto-char (point-min)) (forward-line 4) (point))
     t)))

(defun markdown-stylesheet-link-string (stylesheet-path)
  (concat "<link rel=\"stylesheet\" type=\"text/css\" media=\"all\" href=\""
          stylesheet-path
          "\"  />"))

(defun markdown-add-xhtml-header-and-footer (title)
  "Wrap XHTML header and footer with given TITLE around current buffer."
  (goto-char (point-min))
  (insert "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n"
          "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\"\n"
          "\t\"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd\">\n\n"
          "<html xmlns=\"http://www.w3.org/1999/xhtml\">\n\n"
          "<head>\n<title>")
  (insert title)
  (insert "</title>\n")
  (when (> (length markdown-content-type) 0)
    (insert
     (format
      "<meta http-equiv=\"Content-Type\" content=\"%s;charset=%s\"/>\n"
      markdown-content-type
      (or (and markdown-coding-system
               (fboundp 'coding-system-get)
               (coding-system-get markdown-coding-system
                                  'mime-charset))
          (and (fboundp 'coding-system-get)
               (coding-system-get buffer-file-coding-system
                                  'mime-charset))
          "iso-8859-1"))))
  (if (> (length markdown-css-paths) 0)
      (insert (mapconcat #'markdown-stylesheet-link-string
                         markdown-css-paths "\n")))
  (when (> (length markdown-xhtml-header-content) 0)
    (insert markdown-xhtml-header-content))
  (insert "\n</head>\n\n"
          "<body>\n\n")
  (goto-char (point-max))
  (insert "\n"
          "</body>\n"
          "</html>\n"))

(defun markdown-preview (&optional output-buffer-name)
  "Run `markdown-command' on the current buffer and view output in browser.
When OUTPUT-BUFFER-NAME is given, insert the output in the buffer with
that name."
  (interactive)
  (browse-url-of-buffer
   (markdown-standalone (or output-buffer-name markdown-output-buffer-name))))

(defun markdown-export-file-name (&optional extension)
  "Attempt to generate a filename for Markdown output.
The file extension will be EXTENSION if given, or .html by default.
If the current buffer is visiting a file, we construct a new
output filename based on that filename.  Otherwise, return nil."
  (when (buffer-file-name)
    (unless extension
      (setq extension ".html"))
    (let ((candidate
           (concat
            (cond
             ((buffer-file-name)
              (file-name-sans-extension (buffer-file-name)))
             (t (buffer-name)))
            extension)))
      (cond
       ((equal candidate (buffer-file-name))
        (concat candidate extension))
       (t
        candidate)))))

(defun markdown-export (&optional output-file)
  "Run Markdown on the current buffer, save to file, and return the filename.
If OUTPUT-FILE is given, use that as the filename.  Otherwise, use the filename
generated by `markdown-export-file-name', which will be constructed using the
current filename, but with the extension removed and replaced with .html."
  (interactive)
  (unless output-file
    (setq output-file (markdown-export-file-name ".html")))
  (when output-file
    (let* ((init-buf (current-buffer))
           (init-point (point))
           (init-buf-string (buffer-string))
           (output-buffer (find-file-noselect output-file))
           (output-buffer-name (buffer-name output-buffer)))
      (run-hooks 'markdown-before-export-hook)
      (markdown-standalone output-buffer-name)
      (with-current-buffer output-buffer
        (run-hooks 'markdown-after-export-hook)
        (save-buffer))
      ;; if modified, restore initial buffer
      (when (buffer-modified-p init-buf)
        (erase-buffer)
        (insert init-buf-string)
        (save-buffer)
        (goto-char init-point))
      output-file)))

(defun markdown-export-and-preview ()
  "Export to XHTML using `markdown-export' and browse the resulting file."
  (interactive)
  (browse-url-of-file (markdown-export)))

(defvar markdown-live-preview-buffer nil
  "Buffer used to preview markdown output in `markdown-live-preview-export'.")
(make-variable-buffer-local 'markdown-live-preview-buffer)

(defvar markdown-live-preview-source-buffer nil
  "Source buffer from which current buffer was generated.
This is the inverse of `markdown-live-preview-buffer'.")
(make-variable-buffer-local 'markdown-live-preview-source-buffer)

(defvar markdown-live-preview-currently-exporting nil)

(defun markdown-live-preview-get-filename ()
  "Standardize the filename exported by `markdown-live-preview-export'."
  (markdown-export-file-name ".html"))

(defun markdown-live-preview-window-eww (file)
  "Preview FILE with eww.
To be used with `markdown-live-preview-window-function'."
  (if (require 'eww nil t)
      (progn
        (eww-open-file file)
        (get-buffer "*eww*"))
    (error "EWW is not present or not loaded on this version of Emacs")))

(defun markdown-visual-lines-between-points (beg end)
  (save-excursion
    (goto-char beg)
    (cl-loop with count = 0
             while (progn (end-of-visual-line)
                          (and (< (point) end) (line-move-visual 1 t)))
             do (cl-incf count)
             finally return count)))

(defun markdown-live-preview-window-serialize (buf)
  "Get window point and scroll data for all windows displaying BUF."
  (when (buffer-live-p buf)
    (with-current-buffer buf
      (mapcar
       (lambda (win)
         (with-selected-window win
           (let* ((start (window-start))
                  (pt (window-point))
                  (pt-or-sym (cond ((= pt (point-min)) 'min)
                                   ((= pt (point-max)) 'max)
                                   (t pt)))
                  (diff (markdown-visual-lines-between-points
                         start pt)))
             (list win pt-or-sym diff))))
       (get-buffer-window-list buf)))))

(defun markdown-get-point-back-lines (pt num-lines)
  (save-excursion
    (goto-char pt)
    (line-move-visual (- num-lines) t)
    ;; in testing, can occasionally overshoot the number of lines to traverse
    (let ((actual-num-lines (markdown-visual-lines-between-points (point) pt)))
      (when (> actual-num-lines num-lines)
        (line-move-visual (- actual-num-lines num-lines) t)))
    (point)))

(defun markdown-live-preview-window-deserialize (window-posns)
  "Apply window point and scroll data from WINDOW-POSNS.
WINDOW-POSNS is provided by `markdown-live-preview-window-serialize'."
  (cl-destructuring-bind (win pt-or-sym diff) window-posns
    (when (window-live-p win)
      (with-current-buffer markdown-live-preview-buffer
        (set-window-buffer win (current-buffer))
        (cl-destructuring-bind (actual-pt actual-diff)
            (cl-case pt-or-sym
              (min (list (point-min) 0))
              (max (list (point-max) diff))
              (t   (list pt-or-sym diff)))
          (set-window-start
           win (markdown-get-point-back-lines actual-pt actual-diff))
          (set-window-point win actual-pt))))))

(defun markdown-live-preview-export ()
  "Export to XHTML using `markdown-export'.
Browse the resulting file within Emacs using
`markdown-live-preview-window-function' Return the buffer
displaying the rendered output."
  (interactive)
  (let* ((markdown-live-preview-currently-exporting t)
         (cur-buf (current-buffer))
         (export-file (markdown-export (markdown-live-preview-get-filename)))
         ;; get positions in all windows currently displaying output buffer
         (window-data
          (markdown-live-preview-window-serialize
           markdown-live-preview-buffer)))
    (save-window-excursion
      (let ((output-buffer
             (funcall markdown-live-preview-window-function export-file)))
        (with-current-buffer output-buffer
          (setq markdown-live-preview-source-buffer cur-buf)
          (add-hook 'kill-buffer-hook
                    #'markdown-live-preview-remove-on-kill t t))
        (with-current-buffer cur-buf
          (setq markdown-live-preview-buffer output-buffer))))
    (with-current-buffer cur-buf
      ;; reset all windows displaying output buffer to where they were,
      ;; now with the new output
      (mapc #'markdown-live-preview-window-deserialize window-data)
      ;; delete html editing buffer
      (let ((buf (get-file-buffer export-file))) (when buf (kill-buffer buf)))
      (when (and export-file (file-exists-p export-file)
                 (eq markdown-live-preview-delete-export
                     'delete-on-export))
        (delete-file export-file))
      markdown-live-preview-buffer)))

(defun markdown-live-preview-remove ()
  (when (buffer-live-p markdown-live-preview-buffer)
    (kill-buffer markdown-live-preview-buffer))
  (setq markdown-live-preview-buffer nil)
  ;; if set to 'delete-on-export, the output has already been deleted
  (when (eq markdown-live-preview-delete-export 'delete-on-destroy)
    (let ((outfile-name (markdown-live-preview-get-filename)))
      (when (file-exists-p outfile-name)
        (delete-file outfile-name)))))

(defun markdown-display-buffer-other-window (buf)
  (let ((cur-buf (current-buffer))
        split-width-threshold split-height-threshold)
    (cond ((memq markdown-split-window-direction '(vertical below))
           (setq split-width-threshold nil)
           (setq split-height-threshold 0))
          ((memq markdown-split-window-direction '(horizontal right))
           (setq split-width-threshold 0)
           (setq split-height-threshold nil)))
    (switch-to-buffer-other-window buf)
    (set-buffer cur-buf)))

(defun markdown-live-preview-if-markdown ()
  (when (and (derived-mode-p 'markdown-mode)
             markdown-live-preview-mode)
    (unless markdown-live-preview-currently-exporting
      (if (buffer-live-p markdown-live-preview-buffer)
          (markdown-live-preview-export)
        (markdown-display-buffer-other-window
         (markdown-live-preview-export))))))

(defun markdown-live-preview-remove-on-kill ()
  (cond ((and (derived-mode-p 'markdown-mode)
              markdown-live-preview-mode)
         (markdown-live-preview-remove))
        (markdown-live-preview-source-buffer
         (with-current-buffer markdown-live-preview-source-buffer
           (setq markdown-live-preview-buffer nil))
         (setq markdown-live-preview-source-buffer nil))))

(defun markdown-live-preview-switch-to-output ()
  "Switch to output buffer."
  (interactive)
  "Turn on `markdown-live-preview-mode' if not already on, and switch to its
output buffer in another window."
  (if markdown-live-preview-mode
      (markdown-display-buffer-other-window (markdown-live-preview-export)))
    (markdown-live-preview-mode))

(defun markdown-live-preview-re-export ()
  "Re export source buffer."
  (interactive)
  "If the current buffer is a buffer displaying the exported version of a
`markdown-live-preview-mode' buffer, call `markdown-live-preview-export' and
update this buffer's contents."
  (when markdown-live-preview-source-buffer
    (with-current-buffer markdown-live-preview-source-buffer
      (markdown-live-preview-export))))

(defun markdown-open ()
  "Open file for the current buffer with `markdown-open-command'."
  (interactive)
  (if (not markdown-open-command)
      (error "Variable `markdown-open-command' must be set")
    (if (not buffer-file-name)
        (error "Must be visiting a file")
      (call-process markdown-open-command
                    nil nil nil buffer-file-name))))

(defun markdown-kill-ring-save ()
  "Run Markdown on file and store output in the kill ring."
  (interactive)
  (save-window-excursion
    (markdown)
    (with-current-buffer markdown-output-buffer-name
      (kill-ring-save (point-min) (point-max)))))

\f
;;; Links =====================================================================

(defun markdown-link-p ()
  "Return non-nil when `point' is at a non-wiki link.
See `markdown-wiki-link-p' for more information."
  (let ((case-fold-search nil))
    (and (not (markdown-wiki-link-p))
         (not (markdown-code-block-at-point))
         (or (thing-at-point-looking-at markdown-regex-link-inline)
             (thing-at-point-looking-at markdown-regex-link-reference)
             (thing-at-point-looking-at markdown-regex-uri)
             (thing-at-point-looking-at markdown-regex-angle-uri)))))

(defun markdown-link-link ()
  "Return the link part of the regular (non-wiki) link at point.
Works with both inline and reference style links.  If point is
not at a link or the link reference is not defined returns nil."
  (cond
   ((thing-at-point-looking-at markdown-regex-link-inline)
    (match-string-no-properties 6))
   ((thing-at-point-looking-at markdown-regex-link-reference)
    (let* ((text (match-string-no-properties 3))
           (reference (match-string-no-properties 6))
           (target (downcase (if (string= reference "") text reference))))
      (car (markdown-reference-definition target))))
   ((thing-at-point-looking-at markdown-regex-uri)
    (match-string-no-properties 0))
   ((thing-at-point-looking-at markdown-regex-angle-uri)
    (match-string-no-properties 2))
   (t nil)))

(defun markdown-follow-link-at-point ()
  "Open the current non-wiki link.
If the link is a complete URL, open in browser with `browse-url'.
Otherwise, open with `find-file' after stripping anchor and/or query string."
  (interactive)
  (if (markdown-link-p)
      (let* ((link (markdown-link-link))
             (struct (url-generic-parse-url link))
             (full (url-fullness struct))
             (file link))
        ;; Parse URL, determine fullness, strip query string
        (if (fboundp 'url-path-and-query)
            (setq file (car (url-path-and-query struct)))
          (when (and (setq file (url-filename struct))
                     (string-match "\\?" file))
            (setq file (substring file 0 (match-beginning 0)))))
        ;; Open full URLs in browser, files in Emacs
        (if full
            (browse-url link)
          (when (and file (> (length file) 0)) (find-file file))))
    (error "Point is not at a Markdown link or URI")))

\f
;;; WikiLink Following/Markup =================================================

(defun markdown-wiki-link-p ()
  "Return non-nil if wiki links are enabled and `point' is at a true wiki link.
A true wiki link name matches `markdown-regex-wiki-link' but does
not match the current file name after conversion.  This modifies
the data returned by `match-data'.  Note that the potential wiki
link name must be available via `match-string'."
  (when markdown-enable-wiki-links
    (let ((case-fold-search nil))
      (and (thing-at-point-looking-at markdown-regex-wiki-link)
           (not (markdown-code-block-at-point))
           (or (not buffer-file-name)
               (not (string-equal (buffer-file-name)
                                  (markdown-convert-wiki-link-to-filename
                                   (markdown-wiki-link-link)))))))))

(defun markdown-wiki-link-link ()
  "Return the link part of the wiki link using current match data.
The location of the link component depends on the value of
`markdown-wiki-link-alias-first'."
  (if markdown-wiki-link-alias-first
      (or (match-string-no-properties 5) (match-string-no-properties 3))
    (match-string-no-properties 3)))

(defun markdown-wiki-link-alias ()
  "Return the alias or text part of the wiki link using current match data.
The location of the alias component depends on the value of
`markdown-wiki-link-alias-first'."
  (if markdown-wiki-link-alias-first
      (match-string-no-properties 3)
    (or (match-string-no-properties 5) (match-string-no-properties 3))))

(defun markdown-convert-wiki-link-to-filename (name)
  "Generate a filename from the wiki link NAME.
Spaces in NAME are replaced with `markdown-link-space-sub-char'.
When in `gfm-mode', follow GitHub's conventions where [[Test Test]]
and [[test test]] both map to Test-test.ext.  Look in the current
directory first, then in subdirectories if
`markdown-wiki-link-search-subdirectories' is non-nil, and then
in parent directories if
`markdown-wiki-link-search-parent-directories' is non-nil."
  (let* ((basename (markdown-replace-regexp-in-string
                    "[[:space:]\n]" markdown-link-space-sub-char name))
         (basename (if (eq major-mode 'gfm-mode)
                       (concat (upcase (substring basename 0 1))
                               (downcase (substring basename 1 nil)))
                     basename))
         directory extension default candidates dir)
    (when buffer-file-name
      (setq directory (file-name-directory buffer-file-name)
            extension (file-name-extension buffer-file-name)))
    (setq default (concat basename
                          (when extension (concat "." extension))))
    (cond
     ;; Look in current directory first.
     ((or (null buffer-file-name)
          (file-exists-p default))
      default)
     ;; Possibly search in subdirectories, next.
     ((and markdown-wiki-link-search-subdirectories
           (setq candidates
                 (markdown-directory-files-recursively
                  directory (concat "^" default "$"))))
      (car candidates))
     ;; Possibly search in parent directories as a last resort.
     ((and markdown-wiki-link-search-parent-directories
           (setq dir (locate-dominating-file directory default)))
      (concat dir default))
     ;; If nothing is found, return default in current directory.
     (t default))))

(defun markdown-follow-wiki-link (name &optional other)
  "Follow the wiki link NAME.
Convert the name to a file name and call `find-file'.  Ensure that
the new buffer remains in `markdown-mode'.  Open the link in another
window when OTHER is non-nil."
  (let ((filename (markdown-convert-wiki-link-to-filename name))
        (wp (when buffer-file-name
              (file-name-directory buffer-file-name))))
    (if (not wp)
        (error "Must be visiting a file")
      (when other (other-window 1))
      (let ((default-directory wp))
        (find-file filename)))
    (when (not (eq major-mode 'markdown-mode))
      (markdown-mode))))

(defun markdown-follow-wiki-link-at-point (&optional arg)
  "Find Wiki Link at point.
With prefix argument ARG, open the file in other window.
See `markdown-wiki-link-p' and `markdown-follow-wiki-link'."
  (interactive "P")
  (if (markdown-wiki-link-p)
      (markdown-follow-wiki-link (markdown-wiki-link-link) arg)
    (error "Point is not at a Wiki Link")))

(defun markdown-highlight-wiki-link (from to face)
  "Highlight the wiki link in the region between FROM and TO using FACE."
  (put-text-property from to 'font-lock-face face))

(defun markdown-unfontify-region-wiki-links (from to)
  "Remove wiki link faces from the region specified by FROM and TO."
  (interactive "*r")
  (let ((modified (buffer-modified-p)))
    (remove-text-properties from to '(font-lock-face markdown-link-face))
    (remove-text-properties from to '(font-lock-face markdown-missing-link-face))
    ;; remove-text-properties marks the buffer modified in emacs 24.3,
    ;; undo that if it wasn't originally marked modified
    (set-buffer-modified-p modified)))

(defun markdown-fontify-region-wiki-links (from to)
  "Search region given by FROM and TO for wiki links and fontify them.
If a wiki link is found check to see if the backing file exists
and highlight accordingly."
  (goto-char from)
  (save-match-data
    (while (re-search-forward markdown-regex-wiki-link to t)
      (when (not (markdown-code-block-at-point))
        (let ((highlight-beginning (match-beginning 1))
              (highlight-end (match-end 1))
              (file-name
               (markdown-convert-wiki-link-to-filename
                (markdown-wiki-link-link))))
          (if (condition-case nil (file-exists-p file-name) (error nil))
              (markdown-highlight-wiki-link
               highlight-beginning highlight-end markdown-link-face)
            (markdown-highlight-wiki-link
             highlight-beginning highlight-end markdown-missing-link-face)))))))

(defun markdown-extend-changed-region (from to)
  "Extend region given by FROM and TO so that we can fontify all links.
The region is extended to the first newline before and the first
newline after."
  ;; start looking for the first new line before 'from
  (goto-char from)
  (re-search-backward "\n" nil t)
  (let ((new-from (point-min))
        (new-to (point-max)))
    (if (not (= (point) from))
        (setq new-from (point)))
    ;; do the same thing for the first new line after 'to
    (goto-char to)
    (re-search-forward "\n" nil t)
    (if (not (= (point) to))
        (setq new-to (point)))
    (cl-values new-from new-to)))

(defun markdown-check-change-for-wiki-link (from to)
  "Check region between FROM and TO for wiki links and re-fontify as needed."
  (interactive "*r")
  (let* ((modified (buffer-modified-p))
         (buffer-undo-list t)
         (inhibit-read-only t)
         (inhibit-point-motion-hooks t)
         deactivate-mark
         buffer-file-truename)
    (unwind-protect
        (save-excursion
          (save-match-data
            (save-restriction
              ;; Extend the region to fontify so that it starts
              ;; and ends at safe places.
              (cl-multiple-value-bind (new-from new-to)
                  (markdown-extend-changed-region from to)
                (goto-char new-from)
                ;; Only refontify when the range contains text with a
                ;; wiki link face or if the wiki link regexp matches.
                (when (or (markdown-range-property-any
                           new-from new-to 'font-lock-face
                           (list markdown-link-face
                                 markdown-missing-link-face))
                          (re-search-forward
                           markdown-regex-wiki-link new-to t))
                  ;; Unfontify existing fontification (start from scratch)
                  (markdown-unfontify-region-wiki-links new-from new-to)
                  ;; Now do the fontification.
                  (markdown-fontify-region-wiki-links new-from new-to))))))
      (and (not modified)
           (buffer-modified-p)
           (set-buffer-modified-p nil)))))

(defun markdown-check-change-for-wiki-link-after-change (from to _)
    "Check region between FROM and TO for wiki links and re-fontify as needed.
Designed to be used with the `after-change-functions' hook."
  (markdown-check-change-for-wiki-link from to))

(defun markdown-fontify-buffer-wiki-links ()
  "Refontify all wiki links in the buffer."
  (interactive)
  (markdown-check-change-for-wiki-link (point-min) (point-max)))

\f
;;; Following and Jumping =====================================================

(defun markdown-follow-thing-at-point (arg)
  "Follow thing at point if possible, such as a reference link or wiki link.
Opens inline and reference links in a browser.  Opens wiki links
to other files in the current window, or the another window if
ARG is non-nil.
See `markdown-follow-link-at-point' and
`markdown-follow-wiki-link-at-point'."
  (interactive "P")
  (cond ((markdown-link-p)
         (markdown-follow-link-at-point))
        ((markdown-wiki-link-p)
         (markdown-follow-wiki-link-at-point arg))
        (t
         (error "Nothing to follow at point"))))

(defun markdown-jump ()
  "Jump to another location based on context at point.
Jumps between reference links and definitions; between footnote
markers and footnote text."
  (interactive)
  (cond ((markdown-footnote-text-positions)
         (markdown-footnote-return))
        ((markdown-footnote-marker-positions)
         (markdown-footnote-goto-text))
        ((thing-at-point-looking-at markdown-regex-link-reference)
         (markdown-reference-goto-definition))
        ((thing-at-point-looking-at markdown-regex-reference-definition)
         (markdown-reference-goto-link (match-string-no-properties 2)))
        (t
         (error "Nothing to jump to from context at point"))))

\f
;;; Miscellaneous =============================================================

(defun markdown-compress-whitespace-string (str)
  "Compress whitespace in STR and return result.
Leading and trailing whitespace is removed.  Sequences of multiple
spaces, tabs, and newlines are replaced with single spaces."
  (markdown-replace-regexp-in-string "\\(^[ \t\n]+\\|[ \t\n]+$\\)" ""
                            (markdown-replace-regexp-in-string "[ \t\n]+" " " str)))

(defun markdown-line-number-at-pos (&optional pos)
  "Return (narrowed) buffer line number at position POS.
If POS is nil, use current buffer location.
This is an exact copy of `line-number-at-pos' for use in emacs21."
  (let ((opoint (or pos (point))) start)
    (save-excursion
      (goto-char (point-min))
      (setq start (point))
      (goto-char opoint)
      (forward-line 0)
      (1+ (count-lines start (point))))))

(defun markdown-inside-link-p ()
  "Return t if point is within a link."
  (save-match-data
    (thing-at-point-looking-at (markdown-make-regex-link-generic))))

(defun markdown-line-is-reference-definition-p ()
  "Return whether the current line is a (non-footnote) reference defition."
  (save-excursion
    (move-beginning-of-line 1)
    (and (looking-at-p markdown-regex-reference-definition)
         (not (looking-at-p "[ \t]*\\[^")))))

(defun markdown-adaptive-fill-function ()
  "Return prefix for filling paragraph or nil if not determined."
  (cond
   ;; List item inside blockquote
   ((looking-at "^[ \t]*>[ \t]*\\(\\(?:[0-9]+\\|#\\)\\.\\|[*+:-]\\)[ \t]+")
    (markdown-replace-regexp-in-string
     "[0-9\\.*+-]" " " (match-string-no-properties 0)))
   ;; Blockquote
   ((looking-at "^[ \t]*>[ \t]*")
    (match-string-no-properties 0))
   ;; List items
   ((looking-at markdown-regex-list)
    (match-string-no-properties 0))
   ((looking-at-p markdown-regex-footnote-definition)
    "    ") ; four spaces
   ;; No match
   (t nil)))

(defun markdown-fill-paragraph (&optional justify)
  "Fill paragraph at or after point.
This function is like \\[fill-paragraph], but it skips Markdown
code blocks.  If the point is in a code block, or just before one,
do not fill.  Otherwise, call `fill-paragraph' as usual. If
JUSTIFY is non-nil, justify text as well.  Since this function
handles filling itself, it always returns t so that
`fill-paragraph' doesn't run."
  (interactive "P")
  (unless (or (markdown-code-block-at-point-p)
              (save-excursion
                (back-to-indentation)
                (skip-syntax-forward "-")
                (markdown-code-block-at-point-p)))
    (fill-paragraph justify))
  t)

(defun markdown-fill-forward-paragraph-function (&optional arg)
  (let* ((arg (or arg 1))
         (paragraphs-remaining (forward-paragraph arg))
         (start (point)))
    (when (< arg 0)
      (while (and (not (eobp))
                  (progn (move-to-left-margin) (not (eobp)))
                  (looking-at-p paragraph-separate))
        (forward-line 1))
      (if (looking-at markdown-regex-list)
          (forward-char (length (match-string 0)))
        (goto-char start)))
    paragraphs-remaining))

\f
;;; Extension Framework =======================================================

(defun markdown-reload-extensions ()
  "Check settings, update font-lock keywords and hooks, and re-fontify buffer."
  (interactive)
  (when (eq major-mode 'markdown-mode)
    ;; Update font lock keywords with extensions
    (setq markdown-mode-font-lock-keywords
          (append
           (markdown-mode-font-lock-keywords-math)
           markdown-mode-font-lock-keywords-basic
           (markdown-mode-font-lock-keywords-wiki-links)))
    ;; Update font lock defaults
    (setq font-lock-defaults
          '(markdown-mode-font-lock-keywords
            nil nil nil nil
            (font-lock-syntactic-face-function . markdown-syntactic-face)))
    ;; Refontify buffer
    (when (fboundp 'font-lock-refresh-defaults) (font-lock-refresh-defaults))
    ;; Add or remove hooks related to extensions
    (markdown-setup-wiki-link-hooks)))

(defun markdown-handle-local-variables ()
  "Run in `hack-local-variables-hook' to update font lock rules.
Checks to see if there is actually a ‘markdown-mode’ file local variable
before regenerating font-lock rules for extensions."
  (when (and (boundp 'file-local-variables-alist)
             (assoc 'markdown-enable-wiki-links file-local-variables-alist)
             (assoc 'markdown-enable-math file-local-variables-alist))
    (markdown-reload-extensions)))

\f
;;; Wiki Links ================================================================

(defun markdown-toggle-wiki-links (&optional arg)
  "Toggle support for wiki links.
With a prefix argument ARG, enable wiki link support if ARG is positive,
and disable it otherwise."
  (interactive (list (or current-prefix-arg 'toggle)))
  (setq markdown-enable-wiki-links
        (if (eq arg 'toggle)
            (not markdown-enable-wiki-links)
          (> (prefix-numeric-value arg) 0)))
  (if markdown-enable-wiki-links
      (message "markdown-mode wiki link support enabled")
    (message "markdown-mode wiki link support disabled"))
  (markdown-reload-extensions))

(defun markdown-setup-wiki-link-hooks ()
  "Add or remove hooks for fontifying wiki links.
These are only enabled when `markdown-wiki-link-fontify-missing' is non-nil."
  ;; Anytime text changes make sure it gets fontified correctly
  (if (and markdown-enable-wiki-links
           markdown-wiki-link-fontify-missing)
      (add-hook 'after-change-functions
                'markdown-check-change-for-wiki-link-after-change t t)
    (remove-hook 'after-change-functions
                 'markdown-check-change-for-wiki-link-after-change t))
  ;; If we left the buffer there is a really good chance we were
  ;; creating one of the wiki link documents. Make sure we get
  ;; refontified when we come back.
  (if (and markdown-enable-wiki-links
           markdown-wiki-link-fontify-missing)
      (progn
        (add-hook 'window-configuration-change-hook
                  'markdown-fontify-buffer-wiki-links t t)
        (markdown-fontify-buffer-wiki-links))
    (remove-hook 'window-configuration-change-hook
                 'markdown-fontify-buffer-wiki-links t)
  (markdown-unfontify-region-wiki-links (point-min) (point-max))))

(defun markdown-mode-font-lock-keywords-wiki-links ()
  "Return wiki-link lock keywords if support is enabled.
If `markdown-wiki-link-fontify-missing' is also enabled, we use
hooks in `markdown-setup-wiki-link-hooks' for fontification instead."
  (when (and markdown-enable-wiki-links
             (not markdown-wiki-link-fontify-missing))
    (list
     (cons markdown-regex-wiki-link '((1 markdown-link-face prepend))))))

\f
;;; Math Support ==============================================================

(make-obsolete 'markdown-enable-math 'markdown-toggle-math "v2.1")

(defun markdown-toggle-math (&optional arg)
  "Toggle support for inline and display LaTeX math expressions.
With a prefix argument ARG, enable math mode if ARG is positive,
and disable it otherwise.  If called from Lisp, enable the mode
if ARG is omitted or nil."
  (interactive (list (or current-prefix-arg 'toggle)))
  (setq markdown-enable-math
        (if (eq arg 'toggle)
            (not markdown-enable-math)
          (> (prefix-numeric-value arg) 0)))
  (if markdown-enable-math
      (message "markdown-mode math support enabled")
    (message "markdown-mode math support disabled"))
  (markdown-reload-extensions))

(defun markdown-mode-font-lock-keywords-math ()
  "Return math font lock keywords if support is enabled."
  (when markdown-enable-math
    (list
     ;; Display mode equations with brackets: \[ \]
     (cons markdown-regex-math-display '((1 markdown-markup-face prepend)
                                         (2 markdown-math-face append)
                                         (3 markdown-markup-face prepend)))
     ;; Equation reference (eq:foo)
     (cons "\\((eq:\\)\\([[:alnum:]:_]+\\)\\()\\)" '((1 markdown-markup-face)
                                                     (2 markdown-reference-face)
                                                     (3 markdown-markup-face)))
     ;; Equation reference \eqref{foo}
     (cons "\\(\\\\eqref{\\)\\([[:alnum:]:_]+\\)\\(}\\)" '((1 markdown-markup-face)
                                                           (2 markdown-reference-face)
                                                           (3 markdown-markup-face))))))

\f
;;; GFM Checkboxes ============================================================

(require 'button)

(define-button-type 'markdown-gfm-checkbox-button
  'follow-link t
  'face 'markdown-gfm-checkbox-face
  'mouse-face 'markdown-highlight-face
  'action #'markdown-toggle-gfm-checkbox-button)

(defun markdown-toggle-gfm-checkbox ()
  "Toggle GFM checkbox at point."
  (interactive)
  (save-match-data
    (save-excursion
      (let ((bounds (markdown-cur-list-item-bounds)))
        (when bounds
          ;; Move to beginning of task list item
          (goto-char (cl-first bounds))
          ;; Advance to column of first non-whitespace after marker
          (forward-char (cl-fourth bounds))
          (cond ((looking-at "\\[ \\]")
                 (replace-match "[x]" nil t))
                ((looking-at "\\[[xX]\\]")
                 (replace-match "[ ]" nil t))))))))

(defun markdown-toggle-gfm-checkbox-button (button)
  "Toggle GFM checkbox BUTTON on click."
  (save-match-data
    (save-excursion
      (goto-char (button-start button))
      (markdown-toggle-gfm-checkbox))))

(defun markdown-make-gfm-checkboxes-buttons (start end)
  "Make GFM checkboxes buttons in region between START and END."
  (save-excursion
    (goto-char start)
    (let ((case-fold-search t))
      (save-excursion
        (while (re-search-forward markdown-regex-gfm-checkbox end t)
          (make-button (match-beginning 1) (match-end 1)
                       :type 'markdown-gfm-checkbox-button))))))

;; Called when any modification is made to buffer text.
(defun markdown-gfm-checkbox-after-change-function (beg end _)
  "Add to `after-change-functions' to setup GFM checkboxes as buttons.
BEG and END are the limits of scanned region."
  (save-excursion
    (save-match-data
      ;; Rescan between start of line from `beg' and start of line after `end'.
      (markdown-make-gfm-checkboxes-buttons
       (progn (goto-char beg) (beginning-of-line) (point))
       (progn (goto-char end) (forward-line 1) (point))))))

\f
;;; Display inline image =================================================

(defvar markdown-inline-image-overlays nil)
(make-variable-buffer-local 'markdown-inline-image-overlays)

(defun markdown-remove-inline-images ()
  "Remove inline image overlays from image links in the buffer.
This can be toggled with `markdown-toggle-inline-images'
or \\[markdown-toggle-inline-images]."
  (interactive)
  (mapc #'delete-overlay markdown-inline-image-overlays)
  (setq markdown-inline-image-overlays nil))

(defun markdown-display-inline-images ()
  "Add inline image overlays to image links in the buffer.
This can be toggled with `markdown-toggle-inline-images'
or \\[markdown-toggle-inline-images]."
  (interactive)
  (unless (display-graphic-p)
    (error "Cannot show images"))
  (save-excursion
    (save-restriction
      (widen)
      (goto-char (point-min))
      (while (re-search-forward markdown-regex-link-inline nil t)
        (let ((start (match-beginning 0))
              (end (match-end 0))
              (file (match-string-no-properties 6)))
          (when (file-exists-p file)
            (let* ((abspath (if (file-name-absolute-p file)
                                file
                              (concat default-directory file)))
                   (image (create-image abspath)))
              (when image
                (let ((ov (make-overlay start end)))
                  (overlay-put ov 'display image)
                  (overlay-put ov 'face 'default)
                  (push ov markdown-inline-image-overlays))))))))))

(defun markdown-toggle-inline-images ()
  "Toggle inline image overlays in the buffer."
  (interactive)
  (if markdown-inline-image-overlays
      (markdown-remove-inline-images)
    (markdown-display-inline-images)))

\f
;;; Mode Definition  ==========================================================

(defun markdown-show-version ()
  "Show the version number in the minibuffer."
  (interactive)
  (message "markdown-mode, version %s" markdown-mode-version))

(defun markdown-mode-info ()
  "Open the `markdown-mode' homepage."
  (interactive)
  (browse-url "http://jblevins.org/projects/markdown-mode/"))

;;;###autoload
(define-derived-mode markdown-mode text-mode "Markdown"
  "Major mode for editing Markdown files."
  ;; Natural Markdown tab width
  (setq tab-width 4)
  ;; Comments
  (make-local-variable 'comment-start)
  (setq comment-start "<!-- ")
  (make-local-variable 'comment-end)
  (setq comment-end " -->")
  (make-local-variable 'comment-start-skip)
  (setq comment-start-skip "<!--[ \t]*")
  (make-local-variable 'comment-column)
  (setq comment-column 0)
  (set (make-local-variable 'comment-auto-fill-only-comments) nil)
  ;; Syntax
  (add-hook 'syntax-propertize-extend-region-functions
            'markdown-syntax-propertize-extend-region)
  (add-hook 'jit-lock-after-change-extend-region-functions
            'markdown-font-lock-extend-region-function t t)
  (set (make-local-variable 'syntax-propertize-function)
       'markdown-syntax-propertize)
  ;; Font lock.
  (set (make-local-variable 'markdown-mode-font-lock-keywords) nil)
  (set (make-local-variable 'font-lock-defaults) nil)
  (set (make-local-variable 'font-lock-multiline) t)
  ;; Extensions
  (make-local-variable 'markdown-enable-math)
  ;; Reload extensions
  (markdown-reload-extensions)
  ;; Add a buffer-local hook to reload after file-local variables are read
  (add-hook 'hack-local-variables-hook 'markdown-handle-local-variables nil t)
  ;; For imenu support
  (setq imenu-create-index-function
        (if markdown-nested-imenu-heading-index
            'markdown-imenu-create-nested-index
          'markdown-imenu-create-flat-index))
  ;; For menu support in XEmacs
  (easy-menu-add markdown-mode-menu markdown-mode-map)
  ;; Defun movement
  (set (make-local-variable 'beginning-of-defun-function)
       'markdown-beginning-of-defun)
  (set (make-local-variable 'end-of-defun-function)
       'markdown-end-of-defun)
  ;; Paragraph filling
  (set (make-local-variable 'fill-paragraph-function)
       'markdown-fill-paragraph)
  (set
   ;; Should match start of lines that start or separate paragraphs
   (make-local-variable 'paragraph-start)
       (mapconcat #'identity
                  '(
                    "\f" ; starts with a literal line-feed
                    "[ \t\f]*$" ; space-only line
                    "\\(?:[ \t]*>\\)+[ \t\f]*$"; empty line in blockquote
                    "[ \t]*[*+-][ \t]+" ; unordered list item
                    "[ \t]*\\(?:[0-9]+\\|#\\)\\.[ \t]+" ; ordered list item
                    "[ \t]*\\[\\S-*\\]:[ \t]+" ; link ref def
                    "[ \t]*:[ \t]+" ; definition
                    )
                  "\\|"))
  (set
   ;; Should match lines that separate paragraphs without being
   ;; part of any paragraph:
   (make-local-variable 'paragraph-separate)
   (mapconcat #'identity
              '("[ \t\f]*$" ; space-only line
                "\\(?:[ \t]*>\\)+[ \t\f]*$"; empty line in blockquote
                ;; The following is not ideal, but the Fill customization
                ;; options really only handle paragraph-starting prefixes,
                ;; not paragraph-ending suffixes:
                ".*  $" ; line ending in two spaces
                "^#+"
                "[ \t]*\\[\\^\\S-*\\]:[ \t]*$") ; just the start of a footnote def
              "\\|"))
  (set (make-local-variable 'adaptive-fill-first-line-regexp)
       "\\`[ \t]*>[ \t]*?\\'")
  (set (make-local-variable 'adaptive-fill-regexp) "\\s-*")
  (set (make-local-variable 'adaptive-fill-function)
       'markdown-adaptive-fill-function)
  (set (make-local-variable 'fill-forward-paragraph-function)
       'markdown-fill-forward-paragraph-function)
  ;; Outline mode
  (make-local-variable 'outline-regexp)
  (setq outline-regexp markdown-regex-header)
  (make-local-variable 'outline-level)
  (setq outline-level 'markdown-outline-level)
  ;; Cause use of ellipses for invisible text.
  (add-to-invisibility-spec '(outline . t))

  ;; Inhibiting line-breaking:
  ;; Separating out each condition into a separate function so that users can
  ;; override if desired (with remove-hook)
  (add-hook 'fill-nobreak-predicate
            'markdown-inside-link-p nil t)
  (add-hook 'fill-nobreak-predicate
            'markdown-line-is-reference-definition-p nil t)

  ;; Indentation
  (setq indent-line-function markdown-indent-function)

  ;; Backwards compatibility with markdown-css-path
  (when (boundp 'markdown-css-path)
    (warn "markdown-css-path is deprecated, see markdown-css-paths.")
    (add-to-list 'markdown-css-paths markdown-css-path))

  ;; Prepare hooks for XEmacs compatibility
  (when (featurep 'xemacs)
    (make-local-hook 'after-change-functions)
    (make-local-hook 'font-lock-extend-region-functions)
    (make-local-hook 'window-configuration-change-hook))

  ;; Make checkboxes buttons
  (when markdown-make-gfm-checkboxes-buttons
    (markdown-make-gfm-checkboxes-buttons (point-min) (point-max))
    (add-hook 'after-change-functions 'markdown-gfm-checkbox-after-change-function t t))

  ;; add live preview export hook
  (add-hook 'after-save-hook #'markdown-live-preview-if-markdown t t)
  (add-hook 'kill-buffer-hook #'markdown-live-preview-remove-on-kill t t))

;;;###autoload
(add-to-list 'auto-mode-alist '("\\.markdown\\'" . markdown-mode) t)
;;;###autoload
(add-to-list 'auto-mode-alist '("\\.md\\'" . markdown-mode) t)

\f
;;; GitHub Flavored Markdown Mode  ============================================

(defvar gfm-mode-hook nil
  "Hook run when entering GFM mode.")

(defvar gfm-font-lock-keywords
  (append
   ;; GFM features to match first
   (list
    (cons markdown-regex-strike-through '((3 markdown-markup-face)
                                          (4 markdown-strike-through-face)
                                          (5 markdown-markup-face))))
   ;; Basic Markdown features (excluding possibly overridden ones)
   markdown-mode-font-lock-keywords-basic)
  "Default highlighting expressions for GitHub Flavored Markdown mode.")

;;;###autoload
(define-derived-mode gfm-mode markdown-mode "GFM"
  "Major mode for editing GitHub Flavored Markdown files."
  (setq markdown-link-space-sub-char "-")
  (setq markdown-wiki-link-search-subdirectories t)
  (set (make-local-variable 'font-lock-defaults)
       '(gfm-font-lock-keywords))
  ;; do the initial link fontification
  (markdown-gfm-parse-buffer-for-languages))

\f
;;; Live Preview Mode  ============================================
(define-minor-mode markdown-live-preview-mode
  "Toggle native previewing on save for a specific markdown file."
  :lighter " MD-Preview"
  (if markdown-live-preview-mode
      (markdown-display-buffer-other-window (markdown-live-preview-export))
    (markdown-live-preview-remove)))

\f
(provide 'markdown-mode)
;; Local Variables:
;; indent-tabs-mode: nil
;; End:
;;; markdown-mode.el ends here